v00.0911 HMC983LP5E DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Typical Applications Features (Continued) The HMC983LP5E is suitable for: Integrated Frequency Sweeper - Linear, Coherent Sweeps - 2-Way, 1-Way, & User Defined Sweep Modes - Automatic or Triggered - Programmable Seed -SPI & External Triggering 5-GPIO’s, can be used for External DSM • Test Equipment • Portable Instruments • High Performance Fractional-N Frequency Synthesizers with Ultra Low Spurious • Stand-Alone Divider and/or Delta-Sigma Modulator Features Wideband: DC - 7 GHz Input -20-bit Frequency Divider FREQUENCY DIVIDERS & DETECTORS - SMT 6 6-1 Cycle Slip Prevention Support with PFD Chip (HMC984LP4E) Differential VCO Input & Divider Output Low Noise: -160 dBc/Hz Programmable Output Current Control: -5 mA to 17.5 mA Open Collector Output Driver Low Spurious: Largest Spurious - 95 dBc 32 pin, 5 x 5 mm, LP5 Package 48-bit 100 MHz Delta-Sigma Modulator (DSM) - Configurable DSM Size - Programmable Seed Functional Diagram General Description HMC983LP5E is a fractional frequency divider targeted for fractional-N frequency synthesis, and stand-alone low noise frequency divider applications that require exceptional spurious performance. Although the HMC983LP5E can work with any VCO and/or compatible Phase Detector, best performance and features will be achieved when paired with the companion part, the HMC984LP4E. Fabricated in SiGe BiCMOS process, the HMC983LP5E features a 48-bit Delta Sigma Fractional Modulator (DSM) with programmable phase accumulator size, enabling precise control of frequency step size and resolution. Integrated DSM can generate frequencies with nearly 0 Hz frequency error. The DSM also includes a built-in programmable frequency sweep capability, with various automatic and user defined sweep modes and triggering options, including hardware trigger pin, or SPI trigger with optional delayed trigger. HMC983LP5E is a versatile part capable of various configurations. It has 5 general purpose I/Os (GPIOs). DSM outputs are made available from the GPIO port, enabling the HMC983LP5E to import and/or export DSM sequences for various configuration options. HMC983LP5E divider outputs are differential, open collector with programmable current to accommodate different off-chip loads. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 1. Electrical Specifications TA = +25 °C, AVDD, VCCPS, VCCHF, VDDM, DVDD = 3 V ± 10%; VPPBUF = 5 V ± 10%; GND = 0 V Parameter Conditions Min. Typ. Max. Units 7 GHz 0 dBm 3 pF RF Input Characteristics RF Input Frequency range DC RF Input Sensitivity RF Input Capacitance -15 -10 External Match Recommended Divider Range (20-bit) 32 1,048,575 Fractional Mode 36 1,048,571 Divider Output Characteristics Output Buffer Current Programmable in 2.5 mA Steps 5 12.5 17.5 mA Output Voltage Swing Single- Ended, Vpullup = 5 V 0.75 1 2 V Mode A and Mode B DC DC 150 125 MHz Output Frequency Range Integer Mode Fractional Mode Phase Noise Fractional Spurious 50 MHz PFD, 6 GHz Input, Integer Mode -160 Largest observed at 10 kHz Fractional Offset from Integer Boundary -95 dBc/Hz -85 dBc DVDD-0.4 V Logic Inputs Input High Voltage (VIH) Input Low Voltage (VIL) 0.4 V Logic Outputs Output High Voltage (VOH) DVDD-0.4 Output Low Voltage (VOL) 0.4 V DC Load Serial Port Clock Frequency V Main SPI and AUXSPI 1.5 mA 30 MHz Power Supplies AVDD, VCCPS, VCCHF VPPBUF VDDM, DVDD Analog Supplies. AVDD should be equal to DVDD. 2.7 3 3.3 V Output Buffer Supply. 4.5 5 5.5 V Digital Supplies 2.7 3 3.3 V Current Consumption IDD - Total Current Consumption Integer Mode / Fractional Mode (50 MHz Divider Output) 104 / 122 mA I - AVDD (AVDD Current, 3 V) Integer Mode / Fractional Mode 5/5 mA I - VCCPS (VCCPS Current, 3 V) Integer Mode / Fractional Mode 79 / 79 mA I - VCCHF (VCCHF Current, 3 V) Integer Mode / Fractional Mode 8/8 mA I - VDDM (VDDM Current, 3 V) Integer Mode / Fractional Mode 11 / 11 mA I - DVDD (Total DVDD Current, 3 V) Integer Mode / Fractional Mode 1 / 19 mA 5 uA I - VPPBUF (Total VPPBUF Current, 5 V) For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] 6 FREQUENCY DIVIDERS & DETECTORS - SMT Integer Mode 6-2 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Figure 2. Output Phase Noise, 6 GHz Input Frequency [2] Figure 1. RF Input Sensitivity [1] 40 -60 Maximum Input Power Limit 100 MHz Output Frequency Frac Mode A -80 PHASE NOISE (dBc/Hz) RF INPUT POWER (dBm) 20 0 Recommended Operating Range -20 -40 -60 +27 C +85 C -40 C Minimum Input Power Limit RF Input Signal Phase Noise -160 100 MHz Output Frequency Integer Mode 2000 4000 6000 8000 10000 10 2 10 3 RF INPUT FREQUENCY (MHz) 10 4 10 5 10 6 10 7 10 8 OFFSET FREQUENCY (Hz) Figure 3. Output Phase Noise with 6 GHz Input in Integer Mode [3] Figure 4. Time Domain 10 MHz Output, 6.5 GHz Input [4] -60 5.5 142 MHz Output Frequency -80 OUTOUT VOLTAGE (V) PHASE NOISE (dBc/Hz) divCkPFDp Pin Output -100 RF Input Signal Phase Noise -120 100 MHz Output Frequency -140 -160 5 4.5 50 MHz Output Frequency -180 divCkPFDn Pin Output Calculated Phase Noise -200 10 4 2 10 3 10 4 10 5 10 6 10 7 10 8 0 50 100 150 OFFSET FREQUENCY (Hz) 200 250 300 350 TIME (ns) Figure 5. Time Domain 18 MHz Output, 6.5 GHz Input [4] Figure 6. Time Domain 35 MHz Output, 6.5 GHz Input [4] 5.5 5.5 divCkPFDp Pin Output OUTPUT VOLTAGE (V) divCkPFDp Pin Output OUTPUT VOLTAGE (V) FREQUENCY DIVIDERS & DETECTORS - SMT -140 -200 0 6-3 -120 -180 -80 6 100 MHz Output Frequency Frac Mode B -100 5 4.5 5 4.5 divCkPFDn Pin Output divCkPFDn Pin Output 4 4 0 50 100 TIME (ns) 150 200 0 20 40 60 80 100 TIME (ns) [1] The maximum and minimum levels indicate operational limits of the HMC983LP5E. Performance may degrade with input power greater than 0 dBm for frequencies higher than 6500 MHz. [2] Due to Delta Sigma modulation in fractional mode, the output phase noise peaks at frequency offset of fout/2 from the output. Agilent MXG N5182A used as a signal source. [3] Rohde & Schwarz SMBV100A used as a signal source. [4] Measured with 50 Ω impedance per line, integer Mode, 15 mA Output Buffer Current (Reg 0Fh[4:2]) selected For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Figure 7. Time Domain 124 MHz Output, 6.5 GHz Input [5] Figure 8. Time Domain 66 MHz Output, 6.5 GHz Input [5] 5.5 5.5 divCkPFDp Pin Output OUTPUT VOLTAGE (V) 5 4.5 5 4.5 divCkPFDn Pin Output divCkPFDn Pin Output 4 4 0 5 10 15 20 25 0 30 10 20 Figure 9. Time Domain 61 MHz Output, 6.5 GHz Input [5] 50 6 5.5 divCkPFDp Pin Output OUTPUT VOLTAGE (V) divCkPFDp Pin Output OUTPUT VOLTAGE (V) 40 Figure 10. Time Domain 66 MHz Output, 6.5 GHz Input [5] 5.5 5 4.5 5 4.5 divCkPFDn Pin Output divCkPFDn Pin Output 4 4 0 10 20 30 40 50 0 10 20 TIME (ns) 40 50 Figure 12. 50 MHz Output Swing vs Buffer Current [6] 0.9 SINGLE-ENDED OUTPUT SWING (Vpp) 0.9 0.85 0.8 0.75 0.7 0.65 -40 C 0.6 +27 C 0.55 +85 C 0.85 0.8 0.75 0.7 0.65 -40 C 0.6 +27 C 0.55 +85 C 0.5 0.5 12 30 TIME (ns) Figure 11. 10 MHz Output Swing vs Buffer Current [6] SINGLE-ENDED OUTPUT SWING (Vpp) 30 TIME (ns) TIME (ns) 13 14 15 16 OUTPUT BUFFER CURRENT (mA) 17 18 12 13 14 15 16 17 18 OUTPUT BUFFER CURRENT (mA) [5] Measured with 50 Ω impedance per line, integer Mode, 15 mA Output Buffer Current (Reg 0Fh[4:2]) selected [6] Measured with 50 Ω impedance per line. Buffer current is controled via Reg 0Fh[4:2]. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] FREQUENCY DIVIDERS & DETECTORS - SMT OUTPUT VOLTAGE (V) divCkPFDp Pin Output 6-4 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Figure 13. 100 MHz Output Swing vs Buffer Current [7] Figure 14. Input Return Loss 0 0.85 0.8 RETURN LOSS (dB) SINGLE-ENDED OUTPUT SWING (Vpp) 0.9 0.75 0.7 0.65 -40 C 0.6 0.55 -15 +85 C -20 12 13 14 15 16 17 0 18 2000 4000 Figure 15. Two Way Frequency Sweep, 50 MHz PFD [8] 8000 Figure 16. One Way Frequency Sweep, 10 MHz PFD and 10 Hz external trigger [8] 7000 7000 6900 6900 FREQUENCY (MHz) FREQUENCY (MHz) 6000 FREQUENCY (MHz) OUTPUT BUFFER CURRENT (mA) 6800 6700 6600 6800 6700 6600 6500 6500 6400 6400 0 5 10 TIME (ms) 15 0 20 Figure 17. PLL Cycle Slip Prevention, 100 MHz PFD [8] 200 400 600 TIME (ms) 800 1000 Figure 18. PLL Cycle Slip Prevention, 50 MHz PFD [8] 7050 7050 CSP Enabled Reg0Eh[18:15] = 1h 7000 PLL OUTPUT FREQUENCY (GHz) PLL OUTPUT FREQUENCY (MHz) FREQUENCY DIVIDERS & DETECTORS - SMT 6-5 -10 +27 C 0.5 6 -5 CSP Enabled Reg0Eh[18:15] = 8h 6950 6900 6850 Cycle Slip Disabled 6800 6750 6700 CSP Enabled Reg0Eh[18:15] = Fh 7000 CSP Enabled Reg0Eh[18:15] = 5h 6950 6900 6850 Cycle Slip Disabled 6800 6750 6700 0 50 100 150 TIME (us) 200 250 300 0 50 100 150 200 250 300 TIME (us) [7] Measured with 50 Ω impedance per line. Buffer current is controled via Reg 0Fh[4:2]. [8] Measured with HMC983LP5E/HMC984LP4E chip set as fractional-N synthesizer. Crystal input frequency = 100 MHz, CP current = 2.5 mA, CP offset current = 245 uA, Loop filter bandwidth = 87 KHz, DSM Mode B selected. Cycle Slip Prevention (CSP) is disabled in HMC984LP4E by setting Reg 01h [4] = 0. Setting Reg 01h [4] = 1 enables CSP in the two chip PLL. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 2. Pin Descriptions Function Description 1, 2, 3 SENb SDI SCK Main SPI Data Input 4, 5 D1 D0 GPIO bit 1 GPIO bit 0 6, 7, 8 AUX_SCLK AUX_SENb AUX_SDO 9 BIAS External Decoupling for Analog Bias Circuits 10 AVDD 3 Volt Power Supply Pin for Internal Reference Current Sources 11 VCCPS 3 Volt Power Supply Pin for Prescaler 12, 13 VCOIN, VCIOP Negative Pin for Prescaler Differential Input, AC-Coupled Positive Pin for Prescaler Differential Input, AC-Coupled Interface Schematic Auxiliary SPI Clock Output Auxiliary SPI Enable Auxiliary SPI Data Output 14 VCCHF 3 Volt Power Supply Pin for Prescaler Input Buffer 15 VPPBUF 5 Volt Power Supply Pin for Divider Output Buffer 16 N/C No Connect Pin For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] 6 FREQUENCY DIVIDERS & DETECTORS - SMT Pin Number 6-6 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 2. Pin Descriptions (Continued) Pin Number Function Description 17, 18 divCkPFDn, divCkPFDp Negative Pin for Open Collector Divider Output Driver Positive Pin for Open Collector Divider Output Driver 19 VDDM 3V Supply Pin for Digital Section of the Frequency Divider 20, 21, 22 D2, D3, D4 GPIO bit 2, GPIO bit 3, GPIO bit 4 23 REF_Eno Gate Control (Output) to request TCXO Clock Export from HMC984LP4E 24, 25, 26 CHIP1, CHIP2, CHIP3 Chip Address Pin 1, Chip Address Pin 2, Chip Address Pin 3 27, 30 DVDD 3V Power Supply for Digital 28, DNSAT, VCO Saturation Input flag from HMC984LP4E Chip Interface Schematic FREQUENCY DIVIDERS & DETECTORS - SMT 6 6-7 For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 2. Pin Descriptions (Continued) Pin Number Function Description 29 UPSAT Reference Saturation Input flag from HMC984LP4E Chip Interface Schematic 31 CEN Chip Enable 32 SDO Main SPI Data Output For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] FREQUENCY DIVIDERS & DETECTORS - SMT 6 6-8 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 3. Absolute Maximum Ratings FREQUENCY DIVIDERS & DETECTORS - SMT 6 6-9 Nominal 3V Supplies to GND -0.3 to 3.6 V Nominal 3V Digital Supply to 3V Analog Supply -0.3 to +0.3 V Nominal 5V Supply to GND (VPPBUF) -0.3 to 5.5 V divCkp, divCkn common mode DC VCCPS + 0.5 V min VCOIP, VCOIN Single Ended AC 50 Ω Source + 7 dBm VCOIP, VCOIN Differential AC 50 Ω Source + 13 dBm Digital Input Voltage Range -0.25 to DVDD + 0.5 V Minimum Digital Load 1 kΩ Operating Temperature Range -40 °C to +85 °C Maximum Junction Temperature 125 °C Storage Temperature -65 to +125 °C Thermal Resistance (Rth) (junction to ground paddle) 40 °C/W Reflow Soldering Peak Temperature Time at Peak Temperature 260 °C 40 s ESD Sensitivity (HBM) Class 1B Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTROSTATIC SENSITIVE DEVICE OBSERVE HANDLING PRECAUTIONS Outline Drawing NOTES: [1] PACKAGE BODY MATERIAL: LOW STRESS INJECTION MOLDED PLASTIC SILICA AND SILICON IMPREGNATED. [2] LEAD AND GROUND PADDLE MATERIAL: COPPER ALLOY. [3] LEAD AND GROUND PADDLE PLATING: 100% MATTE TIN. [4] DIMENSIONS ARE IN INCHES [MILLIMETERS]. [5] LEAD SPACING TOLERANCE IS NON-CUMULATIVE. [6] PAD BURR LENGTH SHALL BE 0.15 mm MAX. PAD BURR HEIGHT SHALL BE 0.25 m MAX. [7] PACKAGE WARP SHALL NOT EXCEED 0.05 mm [8] ALL GROUND LEADS AND GROUND PADDLE MUST BE SOLDERED TO PCB RF GROUND. [9] REFER TO HITTITE APPLICATION NOTE FOR SUGGESTED PCB LAND PATTERN. Package Information Part Number Package Body Material Lead Finish MSL Rating [2] Package Marking [1] HMC983LP5E RoHS-compliant Low Stress Injection Molded Plastic 100% matte Sn MSL1 H983 XXXX [1] 4-Digit lot number XXXX [2] Max peak reflow temperature of 260 °C For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Evaluation PCB The circuit board used in the application should use RF circuit design techniques. Signal lines should have 50 Ohms impedance while the package ground leads and exposed paddle should be connected directly to the ground plane similar to that shown unless mentioned otherwise. A sufficient number of via holes should be used to connect the top and bottom ground planes. The evaluation circuit board shown is available from Hittite upon request. Table 4. Evaluation Order Information Item Evaluation Kit Contents HMC983LP5E and HMC984LP4E PLL Chipset Evaluation PCB USB Interface Board 6’ USB A Male to USB B Female Cable CD ROM (Contains User Manual, Evaluation PCB Schematic, Evaluation Software) Part Number EKIT01-HMC983LP5E For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 10 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Evaluation PCB Block Diagram FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 11 For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Theory of Operation The HMC983LP5E can be used in following configurations: 1. Fractional-N or Integer Mode RF Frequency Divider or Prescaler 2. Fractional-N Frequency Synthesizer with an appropriate Phase Detector and VCO Primary target application of the HMC983LP5E is to be used in conjunction with the HMC984LP4E as shown in Figure 19. Together these two components form a high performance, low noise, ultra low spurious emissions fractional-N frequency synthesizer. Figure 19. Typical Application of HMC984LP4E with HMC983LP5E to Form a Frequency Synthesizer The HMC983LP5E consists of the following functional blocks 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. RF Input Buffer 7 GHz Frequency Prescaler and Multi Modulus Divider 48-bit Configurable Fractional Delta Sigma Modulator Bias Circuit Differential Output Driver Frequency Sweeper Main Serial Port Interface Auxiliary Serial Port Interface (Output Only) General Purpose Digital IO Power On Reset Circuit RF Input Buffer The RF input stage provides the path from the external VCO to the fractional RF Divider. The RF input path is rated to operate nominally from DC to 7 GHz. The HMC983LP5E RF input stage is a differential common emitter stage with DC coupling, and is protected by ESD diodes as shown in Figure 20. RF input is not matched to 50 Ω due to wide input frequency range. At low frequencies, a simple shunt 50 Ω resistor can be used external to the package to provide a 50 Ω match. For better performance it is recommended to match the RF inputs externally and provide differential drive from the VCO. In most applications the input is used single-ended into either the VCOIP or VCOIN pin with the other input connected to ground through a DC blocking capacitor. The preferred input level for best spectral performance is -10 dBm. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 12 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER 6 FREQUENCY DIVIDERS & DETECTORS - SMT Figure 20. RF Input Stage 6 - 13 RF Path Fractional-N Divider The RF input buffer is followed by a high frequency prescaler and a multi modulus divider. The divider has been designed for the best output phase noise and spurious performance in both fractional and integer mode. The fractional-N divider can divide input frequencies from 32 to 220 -1 (1048575) in integer mode and from 36 to 220 -5 (1048571) in fractional-N mode. The divider output pulse width depends on the RF input period and is adjustable via SPI setting (refer to Duty Cycle Setting in register Reg 0Fh[14:12]). The output pulse width recommended setting is 40% to 60% where possible. At low output frequencies it may not be possible to set 50% duty cycle. In such cases the maximum pulse width setting is recommended. Figure 21. Divider Path Divider Output Buffer The divider output is differential and the output buffer stage is an open collector amplifier with off-chip pull-up resistors. Due to sharp rise and fall times at the divider output, the external path should be designed differentially using RF techniques. When HMC983LP5E and HMC984LP4E are operating together as a frequency synthesizer, 50 Ω pull-up resistors are provided in HMC984LP4E. VPPBUF pin should be connected to 5 V power supply. This pin does not sink DC current and is only used to bias the internal ESD diodes and to provide an appropriate voltage level for the phase detector chip (HMC984LP4E). The two possible interface configurations are shown in Figure 22 and Figure 23 below. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Figure 22. Generic Divider Output Interface Figure 23. Divider Interface with HMC984LP4E Chip Address Pins The HMC983LP5E has three SPI chip address pins (SPI address [2:0] = ‘CHIP3, CHIP2, CHIP1’), which enable multiple HMC983LP5E devices to use the same SPI bus. SPI chip address bits are read at power up, or every time HMC983LP5E is reset. By default, all three pins are internally pulled to DVDD, thus there is no need to connect the pins to DVDD to set them to logic high. To assign a ‘0’ to any chip address bit, the corresponding pin should be connected to ground. When used on the same SPI bus together with the companion part (the HMC984LP4E), to form a frequency synthesizer, some SPI commands, such as changing the reference division ratio to the HMC984LP4E may also require an action by the HMC983LP5E. In order to avoid the necessity to write two separate SPI transfers to implement one command (one to configure HMC984LP4E, and the other one to configure the HMC983LP5E), it is possible to write the SPI address of the companion part (HMC984LP4E) into Reg 09h of the HMC983LP5E. In such cases, the HMC983LP5E is able to recognize an SPI command to the companion part (the HMC984LP4E) that requires its own action, and act accordingly to update its own corresponding registers. Writing HMC983LP5E’s own chip address to the companion chip address register Reg 09h will disable this feature. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 14 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Saturation Detection Input Pins DNSAT, UPSAT When the HMC983LP5E is operating with its companion chip the HMC984LP4E as a frequency synthesizer, it automatically detects large phase errors and tries to tune the VCO faster by using its algorithm for cycle-slip prevention (CSP). The UPSAT and DNSAT provide indication which frequency is higher (VCO or Reference) from the counterpart Phase Detector/Charge Pump (the HMC984LP4E). The CSP algorithm manipulates the RF Divider and the Phase Detector at appropriate intervals to lock faster. See HMC984LP4E data sheet for more details. These pins should be connected to ground if not used. REF_Eno Pin REF_Eno pin is a digital output pin that is used by the HMC983LP5E to request crystal oscillator clock from the Phase Detector / Charge Pump chip (the HMC984LP4E). FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 15 The crystal oscillator clock is multiplexed on the HMC983LP5E’s DNSAT pin. The internal frequency divider, programmed in Reg 02h, is used to generate the actual reference frequency present at the phase detector. The imported clock is only used to communicate through the AUXSPI. At all other times, the clock and the local reference dividers are turned off. In stand-alone applications, if the HMC983LP5E is required to communicate through the auxiliary SPI, the HMC983LP5E will expect to receive the auxiliary SPI clock on DNSAT pin. Setting Reg 04h[15] = 1 keeps the auxiliary SPI clock enabled on the DNSAT pin. Multi Purpose Digital IO Pins D0, D1, D2, D3, D4 (GPIO Pins) The five general purpose digital input/outputs can be used for various modes of operation as well as test/debugging purposes. GPIO pins are enabled by writing Reg 01h[4] = 1 (GPIO master enable). Setting Reg 01h[4] = 0 places the GPIO pins in tri-state high impedance mode. GPIO pins are configured in Reg 08h[13:0]. All of the pins can configured to be either inputs or outputs by writing to Reg 08h[13:9]. In frequency sweep mode, pin D4 can be used as an external trigger pin, by writing Reg 08h[13] = 0. Writing to Reg 08h[3:0] selects HMC983LP5E’s internal signals to be multiplexed out on the GPIO pins, as shown in Table 5. Signals include: 1. The output of the Delta-Sigma Modulator Reg 08h[3:0] = ‘0010’b. 2. GPIO test signals Reg 08h[3:0] = ‘0000’b, which outputs data written to Reg 08h[8:4] to test the GPIO pins. 3. Sweep status flags, when the HMC983LP5E is configured to be in sweep mode Reg 08h[3:0] = ‘1000’b. Table 5. GPIO Pin Assignment and Output Signals Reg 08h[3:0] HMC983LP5E GPIO Pins D4 D3 D2 D1 D0 0000 gpo_test_out[4] gpo_test_out[3] gpo_test_out[2] gpo_test_out[1] gpo_test_out[0] 0001 reserved reserved reserved reserved reserved 0010 DSM_OUT[4] DSM_OUT[3] DSM_OUT[2] DSM_OUT[1] DSM_OUT[0] 0011 reserved reserved reserved reserved reserved 0100 reserved reserved reserved reserved reserved 0101 reserved reserved reserved reserved reserved 0110 reserved reserved reserved 0 0 0111 reserved reserved reserved reserved reserved 1000 ramp_ready_flag ramp_start_flag ramp_stop_flag ramp_busy_falg reserved 1001-1111 0 0 0 0 0 For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Fractional Mode of Operation In addition to providing simple integer division ratios, the HMC983LP5E has a sophisticated, configurable 48-bit Delta Sigma Modulator (DSM), that allows fractional division of the input frequency in ultra fine steps. The DSM’s size can be configured to 16/24/32/48 bits (Reg 16h[5:0]). HMC983LP5E’s auto-seed mode allows coherent frequency sweeps. The HMC983LP5E with its counterpart (the HMC984LP4E), together with an external VCO comprise a fully functional fractional-N synthesizer. In that case, the output frequency of the external VCO is given by: fvco = fxtal f ⋅ Nint + xtal L ⋅ Nfrac = fint + ffrac R R⋅2 (Eq 1) When the HMC983LP5E is being used as frequency divider, the output frequency is given by; Nint fvco N + frac 2L (Eq 2) Where f vco is the VCO frequency in Hz; fxtal is the crystal oscillator frequency in Hz; Nint is the integer part of frequency division ratio (set in Reg 05h[19:0]); Nfrac is the fractional part of frequency division ratio (Nfrac[47:18] = Reg 06h[29:0], Nfrac[17:0] = Reg 07h[17:0]) R is the reference frequency division ratio; L is the size of the DSM accumulators (set in Reg 16h[5:0]) Example 1: Calculate the VCO frequency with the following parameters; fxtal = 50 MHz; fpfd = 25 MHz Nint = 25; Nfrac = 1; L = 24 Where fPFD is the frequency at the phase detector, thus R = 2. According to (Eq 1), the VCO frequency with the above parameters will be; 50MHz 50MHz ⋅ 25 + ⋅ 1 = 2500MHz + 1.49Hz 2 2 ⋅ 224 If accumulator width (L) is changed to 48-bit, then the frequency resolution will improve and the fractional resolution of the VCO frequency will be 88.8178 nano-Hz. fvco = Example 2: Set the VCO frequency to 4600.025 MHz using 100 MHz Crystal, R = 2 and L = 16. Compare if L = 32. For this example the fPFD = 100 MHz/2 = 50 MHz, The overall division ratio is 4600.025 MHz/50 MHz = 92.0005 The nearest integer would be 92, thus Nint = Reg 05h[19:0] = 92d = 5Ch. For L = 16, Nfrac = 32.768 or 33d rounded up. Thus Nfrac = 33d or 21h (Reg 06h[29:0] = 0, Reg 07h[17:0] = 21h). For L = 32, Nfrac = 2147483.648 or 2147484d rounded up. Thus Nfrac = 20C49Ch (Reg 06h[29:0] = 8h, Reg 07h[17:0] = ‘001100010010011100‘d). Since Nfrac must be an integer, the actual frequencies in the two cases will have an error of + 177.02 Hz for L = 16 and only +0.004098 Hz for L = 32. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] 6 FREQUENCY DIVIDERS & DETECTORS - SMT fout = 6 - 16 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Phase Noise in Integer and Fractional Modes In a normal integer frequency divider the in-band phase noise is scaled from the input phase noise by 20Log10(N), where N is the divider value. In HMC983LP5E fractional mode, the frequency divider is modulated by the Delta Sigma Modulator to generate output frequencies that are fractional multiple of the input frequency. Delta Sigma Modulator shapes the quantization noise such that quantization noise density has a high pass shape which peaks at Fs/2, where Fs is the sampling frequency (the divider output frequency in case of HMC983LP5E). In fractional mode this quantization noise peak appears at an offset frequency of Fout/2. In the PLL, this peak is attenuated by the loop filter. However, when the HMC983LP5E is used stand-alone in fractional mode its output will exhibit the quantization noise as shown in Figure 2 and Figure 3. As a result, it is not possible to achieve the same noise floor in fractional mode as in integer mode without further filtering. CW Frequency Sweeper 6 The HMC983LP5E features a built-in frequency sweeper function that supports automatic or externally triggered sweeps. External triggering can be executed via an external trigger pin D4 or the SPI interface. HMC983LP5E sweep function can be configured to operate in the following modes: FREQUENCY DIVIDERS & DETECTORS - SMT • 6 - 17 • 2-Way sweep mode • Repeating alternating positive and negative frequency sweep ramps • Frequency increments swept with automatic sequencer • Automatic or triggered • Symmetric or asymmetric (the positive ramp can have a different slope from that of the negative ramp) 1-Way Sweep Mode • Repeating one directional frequency sweeps followed by a reset to the starting frequency • Frequency increments swept with automatic sequencer • Triggered User defined sweep mode • Manually programmed user defined sweep patterns • Triggered • Symmetric or asymmetric (the positive ramp can have a different slope from that of the negative ramp) In all sweep modes, the starting sweep direction can be set to positive (increasing) or negative (decreasing). The trigger can be applied instantaneously or delayed by a programmable time delay. HMC983LP5E’s sweep function is illustrated in Figure 24. The HMC983LP5E generates a frequency sweep by implementing automatic, or triggered in User Defined Mode, discrete miniature frequency increments in time. A smooth and continuous sweep is then generated, at the output of the VCO, after the stepped signal is filtered by the loop filter, as shown in Figure 24. The stepped sweep approach enables the frequency synthesizer (comprising of HMC983LP5E together with its counterpart, the HMC984LP4E) to be in lock for the entire duration of the sweep. This approach results in a number of advantages over conventional methods including: • The ability to generate a linear sweep. • The ability to have phase coherence between different sweep ramps, so that the phase profile of each sweep is identical. • The ability to generate user defined sweeps in User Defined Sweep Mode. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Figure 24. HMC983LP5E Sweep Function It is important to note that the synthesized ramp is subject to normal phase locked loop dynamics. If the loop bandwidth in use is much wider than the rate of frequency increments then the locking will be fast and the ramp will have a staircase shape. If the update rate is higher than the loop bandwidth, as is normally the case, the loop will not fully settle before a new frequency step is received. Hence the swept output will have a lag and will sweep in a near continuous fashion. In all sweep modes, ramp_busy flag indicates an active sweep and will stay high between the 1st and nth ramp increment. ramp_busy may be monitored on pin D1 by setting Reg 08h[3:0] = 8h. Triggering In sweep mode, the HMC983LP5E can be triggered via one of two methods • SPI trigger by setting Reg 0Eh[12]=1. This triggering method is asynchronous to the reference clock. To enable SPI trigger write Reg 0Eh[13] = 0. • or applying an external trigger on pin D4. Setting Reg 0Eh[13] = 1 and Reg 08h[13] = 0h configures HMC983LP5E’s pin D4 as external trigger input. External trigger on pin D4 is triggered on the rising edge of the trigger. GPIO master enable (Reg 01h[4] = 1) is also required. • External triggering method can be synchronized with the reference clock, by enabling trigger delay (Reg 0Eh [7] = 1), and programming a trigger delay in Reg 05h[20:0] = number of delayed reference periods. Writing Reg 05h[20:0] = 1 for example ensures that the trigger is applied at the instant of the rising edge of the next reference rising edge. To disable trigger delay write Reg 0Eh [7] = 0. 2-Way Sweep Mode HMC983LP5E’s 2-Way sweep mode is shown in Figure 25. The 2-Way sweep mode can be automatic or triggered. In automatic 2-way sweep, the trigger is generated internally based on user defined 2-way sweep mode configuration. In a triggered 2-way sweep, frequency ramps are triggered either by external pin D4, or SPI trigger. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 18 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 19 Figure 25. HMC983LP5E 2-Way Triggered Sweep Triggered 1-Way Sweeps HMC983LP5E’s 1-Way sweeps is shown in Figure 26. Unlike 2-Way sweeps, 1-Way sweeps require that the VCO hop back to the start frequency after the dwell period. Triggered 1-Way sweeps also require a 3rd trigger to start the new sweep. The 3rd trigger must be timed appropriately to allow the VCO to settle after the large frequency hop back to the start frequency. Subsequent odd numbered triggers will start each sweep and repeat the process. Figure 26. HMC983LP5E 1-Way Triggered Sweep 1-Way sweeps are not recommended in auto-sweep mode since in auto-sweep the new sweep will start immediately after the 2nd trigger, as it does in 2-Way mode. User Defined Sweep Mode In User Defined Sweep mode, the HMC983LP5E is able to generate various user-defined sweep patterns by adjusting the time interval between adjacent frequency increments, which are executed by trigger events. HMC983LP5E’s User Defined Sweep Mode is shown in Figure 27. In this mode, an external trigger is required for each frequency increment of the sweep. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Figure 27. HMC983LP5E User Defined Sweep User defined sweep can function in both 1-Way or 2-Way sweep mode. In 1-Way sweep mode, the n+1 trigger will cause the ramp to jump to the start frequency, and the n+2 trigger will restart the 1-way sweep. Detailed Sweeper Configuration Recommended procedure for configuring HMC983LP5E sweeper in all three modes is shown in Table 6. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 20 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 6. HMC983LP5E Sweeper Configuration Sequence Steps 1 2 FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 21 3 Description Lock to start frequency (fo) Place the DSM in sweep mode Configure sweep mode Sweeper Modes 2-Way Sweep Mode User Defined Sweep Mode 1-Way Sweep Mode •set the integer (Reg 05h) and fractional (Reg 06h and Reg 07h) divider values. •Optionally, if required the seed (Reg 0Ah and Reg 0Bh) can also be programmed •Write Reg 0Eh[11] = 1 •Disable single step ramp mode (Reg 0Eh[24] = 0), so that each frequency increment will be incremented automatically •Enable 2-way sweep mode (Disable 1-way sweep mode (Reg 0Eh[25] = 0)) •To place the HMC983LP5E in automatic sweep mode write Reg 0Eh[2:3] = ‘11’. To place the HMC983LP5E in triggered mode write Reg 0Eh[2:3] = ‘00’. •Enable the single step ramp mode (Reg 0Eh[24] = 1), so that each frequency increment will require a trigger •Enable 1-way sweep mode (Reg 0Eh[25] = 1), or enable 2-Way sweep mode (Reg 0Eh[25] = 1) •To place the HMC983LP5E in triggered mode write Reg 0Eh[2:3] = ‘00’. Automatic User Defined Sweep mode is not supported. •Disable single step ramp mode (Reg 0Eh[24] = 0), so that each frequency increment will be incremented automatically •Enable 1-way sweep 0Eh[25] = 1) mode (Reg •To place the HMC983LP5E in triggered mode write Reg 0Eh[2:3] = ‘00’. Automatic 1-Way Sweep mode is not supported. 4 Program Sweep Direction 5 Configure symmetrical/ asymmetrical sweep 6 Program Up Sweep Parameters 7 Program Down Sweep Parameters (Only if using asymmetrical sweep (if Reg 0Eh[22] = 0) in Step 5) •Set dwell time (dwell time[47:0] = Reg 06h[47:18], dwell time[17:0] = Reg 07h[17:0]) •Set step size (step size[47:18] = Reg 19h[29:0], step size[17:0] = Reg 1Ah[17:0]) •Set the number of steps in a sweep (number of steps[47:18] = Reg 0Ch[29:0], number of steps[17:0] = Reg 0Dh[17:0]) Configure and apply trigger •To use SPI trigger write Reg 0Eh[13] = 0 to select SPI trigger. SPI trigger is executed by writing to Reg 0Eh[12] = 1. •To use external trigger on pin D4 write Reg 0Eh[13] = 1 to configure pin D4 as an external trigger. Write Reg 08h[13] = 0h to configure pin D4 to be an input. Applying master enable to GPIO pins (Reg 01h[4] = 1 ) is required. •Enable trigger delay (Reg 0Eh[7] = 1), or disable trigger delay (Reg 0Eh[7] = 0). •If using trigger delay, write delay value to Reg 05h[20:0], where Reg 05h[20:0] = number of delayed reference periods. Writing Reg 05h[20:0] = 1 for example ensures that the trigger is applied at the instant of the rising edge of the next reference rising edge. 8 •Reg 0Eh[26] = 1 begin sweep in positive direction, Reg 0Eh[26] = 0 begin sweep in negative direction •Program ramp mode (symmetrical - Reg 0Eh[22] = 1, asymmetrical - Reg 0Eh[22] = 0). If symmetrical ramp mode is selected (Reg 0Eh[22] = 1), only Up sweep parameters will be used for both positive and negative sweeps, and hence down sweep parameters don’t need to be programmed. In symmetrical ramp mode the positive and negative ramps are identical and opposite in direction. •Program Reg 0Eh[22] = 1. Asymmetrical sweep is not defined in 1-Way Sweep mode •Set dwell time(dwell time[47:0] = Reg 10h[29:0], dwell time[17:0] = Reg 11h[17:0]) •Set step size (step size[47:18] = Reg 12h[29:0], step size[17:0] = Reg 13h[17:0]) •Set the number of steps in a sweep (number of steps[47:18] = Reg 14h[29:0], number of steps[17:0] = Reg 15h[17:0]) •Asymmetrical sweep is not defined in 1-Way Sweep mode HMC983LP5E sweep parameters are defined in the following way: fo Initial frequency of the synthesizer For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER ff Frequency of the synthesizer at the end of the sweep R Reference divider value(Reg 02h[13:0]) stepsize frequency increment step size. In case of symmetric and UP sweeps, stepsize[47:18] = Reg 12h[29:0], stepsize[17:0] = Reg 13h[17:0]). In case of asymmetric sweeps, (downsweep stepsize[47:18] = Reg 12h[29:0], down sweep stepsize[17:0] = Reg 13h[17:0]) ∆fstep Frequency step size = L Size of the DSM (set in Reg 16h[5:0]) Tref Period of the divided reference (fPFD) at the phase detector. Tref = stepsize ⋅ 2L ⋅ R , R fxtal N Total number of frequency step increments in a single sweep. N [47:18] = Reg 14h[29:0], N[17:0] = Reg 15h[17:0] Total time of one frequency sweep from fo to ff. Tramp = Tref x N Tramp Then final frequency ff is given by: ff = fo + (∆fstep x N) Setting autoseed (Reg 0Eh[8] = 1) ensures that different sweeps have identical phase profile. This is achieved by loading the seed (seed[47:18] = Reg 0Ah[29:0], seed[17:0] = Reg 0Bh[17:0]) into the phase accumulator at the beginning of each ramp. Example: Calculate sweep parameters for an asymmetric 2-Way sweep from f0 = 3000 MHz to ff = 3105 MHz with positive Tramp ≈ 2 ms, and negative Tramp ≈ 4 ms, and positive dwell time = negative dwell time = 2 µs, with fPD = 50 MHz, and a 48-bit delta-sigma modulator size. Assuming R = 1. 1. Calculate the integer and fractional divider values for initial start frequency f0 • Start Nint = Reg 05h = 60d • Start Nfrac = Reg 06h = Reg 07h = 0d 2. Calculate the number of divided (R = 1) reference periods in the sweep = number of frequency increments N • Nup = 2 ms/(1/50 MHz) = 100000 • Ndown = 4 ms/(1/50 MHz) = 200000 3. Calculate stepsize (size of frequency increments) • stepssize up = abs(ff - f0)/Nup = abs(3000 MHz - 3105 MHz)/100000 = 1050 Hz. Then as per Table 6, Reg 12h[29:0] = 0h, Reg 13h[17:0] = 1050d = 41Ah • stepsize down = abs(ff - f0)/Ndown = abs(3000 MHz - 3105 MHz)/200000 = 525 Hz Then as per Table 6, Reg 19h[29:0] = 0h, Reg 1Ah[17:0] = 1050d = 41Ah Note that it is possible to have a case where the frequency ff cannot be generated exactly. In that case it is required to approximate the final frequency to ff = fo + (∆fstep x N) ≈ desired final frequency. 4. Calculate number of divided (R = 1) reference periods in required dwell time • Up dwell time (Reg 10h[29:0], Reg 11h[17:0]) = down dwell time (Reg 06h[29:0], Reg 07h[17:0]) = dwell time/ (1/ 50 MHz) = 2 µs/(1/50 MHz) = 100. Then as per Table 6, Reg 10h[29:0] = Reg 06h[29:0] = 0h, and Reg 11h[17:0] = Reg 07h[17:0] = 100d = 64h. Then proceed to configure the sweep according to the steps outlined in Table 6. Serial Port Interface The HMC983LP5E features a four wire serial port for simple communication with the host controller. Typical serial port operation can be run with SCK at speeds up to 30 MHz. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] 6 FREQUENCY DIVIDERS & DETECTORS - SMT fxtal 6 - 22 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER The details of SPI access for the HMC983LP5E is provided in the following sections. Note that the READ operation below is always preceded by a WRITE operation to Register 0 to define the register to be queried. Also note that every READ cycle is also a WRITE cycle in that data sent to the SPI while reading the data will also be stored by the HMC983LP5E when SENb goes high. If this is not desired then it is suggested to write to Register 0 during the READ operation so that the status of the device will be unaffected. Power on Reset and Soft Reset The HMC983LP5E has a built in Power On Reset (POR) and a serial port accessible Soft Reset (SR). POR is accomplished when power is cycled for the HMC983LP5E while SR is accomplished via the SPI by writing Reg 00h = 80h, followed by writing Reg 00h =00h. All chip registers will be reset to default states approximately 250 us after power up. FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 23 Serial Port WRITE Operation The host changes the data on the falling edge of SCK and the HMC983LP5E reads the data on the rising edge. A typical WRITE cycle is shown in Figure 28. It is 32 clock cycles long. 1. The host both asserts SENb (active low Serial Port Enable) and places the MSB of the data on SDI followed by a rising edge on SCK. 2. HMC983LP5E reads SDI (the MSB) on the 1st rising edge of SCK after SENb. 3. HMC983LP5E registers the data bits, D23:D0, in the next 23 rising edges of SCK (total of 24 data bits). 4. Host places the 5 register address bits, A4:A0, on the next 5 falling edges of SCK (MSB to LSB) while the HMC983LP5E reads the address bits on the corresponding rising edge of SCK. 5. Host places the 3 chip address bits, CA2:CA0=[110], on the next 3 falling edges of SCK (MSB to LSB). Note the HMC983LP5E chip address is fixed as “6d” or “110b”. 6. SENb goes from low to high after the 32nd rising edge of SCK. This completes the WRITE cycle. 7. HMC983LP5E also exports data back on the SDO line. For details see the section on READ operation. Serial Port READ Operation The SPI can read from the internal registers in the chip. The data is available on SDO pin. This pin itself is tri-stated when the device is not being addressed. However when the device is active and has been addressed by the SPI master, the HMC983LP5E controls the SDO pin and exports data on this pin during the next SPI cycle. HMC983LP5E changes the data to the host on the rising edge of SCK and the host reads the data from HMC983LP5E on the falling edge. A typical READ cycle is shown in Figure 28. Read cycle is 32 clock cycles long. To specifically read a register, the address of that register must be written to dedicated Reg 0h. This requires two full cycles, one to write the required address, and a 2nd to retrieve the data. A read cycle can then be initiated as follows; 1. The host asserts SENb (active low Serial Port Enable) followed by a rising edge SCK. 2. HMC983LP5E reads SDI (the MSB) on the 1st rising edge of SCK after SENb. 3. HMC983LP5E registers the data bits in the next 23 rising edges of SCK (total of 24 data bits). The LSBs of the data bits represent the address of the register that is intended to be read. 4. Host places the 5 register address bits on the next 5 falling edges of SCK (MSB to LSB) while the HMC983LP5E reads the address bits on the corresponding rising edge of SCK. For a read operation this is “00000”. 5. Host places the 3 chip address bits [110] on the next 3 falling edges of SCK (MSB to LSB). 6. SENb goes from low to high after the 32nd rising edge of SCK. This completes the first portion of the READ cycle. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER 7. The host asserts SENb (active low Serial Port Enable) followed by a rising edge SCK. 8. HMC983LP5E places the 24 data bits, 5 address bits, and 3 chip id bits, on the SDO, on each rising edge of the SCK, commencing with the first rising edge beginning with MSB. 9. The host de-asserts SENb (i.e. sets SENb high) after reading the 32 bits from the SDO output. The 32 bits consists of 24 data bits, 5 address bits, and the 3 chip id bits. This completes the read cycle. Note that the data sent to the HMC983LP5E SPI during this portion of the READ operation is stored in the SPI when SENb is de-asserted. It is recommended that during the second phase of the READ operation that Reg 00h is addressed with either the same address or the address of another register to be read during the next cycle. Figure 28. SPI Timing Diagram DVDD = 5 V ±10%, GND = 0 V Table 7. Main SPI Timing Characteristics Parameter Conditions t1 SDI to SCK Setup Time t2 t3 Min Typ Max Units 8 nsec SDI to SCK Hold Time 8 nsec SCK High Duration [1] 10 nsec t4 SCK Low Duration 10 nsec t5 SENb Low Duration 20 nsec t6 SENb High Duration 20 nsec t7 SCK to SENb [2] 8 nsec t8 SCK to SDO out [3] 8 nsec [1] The SPI is relatively insensitive to the duty cycle of SCK. [2] SENb must rise after the 32nd falling edge of SCK but before the next rising SCK edge. If SCK is shared amongst several devices this timing must be respected. [3] Typical load to SDO is 10 pF, maximum 20 pF For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 24 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Register Map Table 8. Reg 00h Chip ID, Soft Reset, Read Register BIT TYPE [6:0] R/W [7] [31:8] NAME W DEFLT DESCRIPTION Read Register Address 7 0 Address of the register to be read in the next cycle. R/W Soft Reset 1 0 Soft Reset. Writing 1 generates soft reset. Resets all the digital and registers to default states. Writing 0 resumes normal chip operation. R/W Chip ID 24 97330h Part Number, Description. Read reg00h returns chip ID. Table 9. Reg 01h - Settings Register FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 25 BIT TYPE NAME W DEFLT [0] R/W VCO Buffer Enable 1 1 Enables VCO input RF buffer. DESCRIPTION [1] R/W Reserved 1 1 Write 0 to this bit. [2] R/W AUXSPI Enable 1 1 Enables Auxiliary SPI. [3] R/W Sigma Delta Enable 1 1 Enables Sigma Delta Function. [4] R/W GPIO Enable 1 1 Enables output from all GPIO pins. [5] R/W RF Divider Enable 1 1 Enables RF Divider. [6] R/W Output Buffer Enable 1 1 Enables Divider Output Driver. [7] R/W Bias Enable 1 1 Enables bias generator for all blocks. [8] R/W PSCLK to Digital Enable 1 1 Enable Prescaler clock going to digital counters. [9] R/W Unused 1 1 Table 10. Reg 02h R-Divider Register BIT TYPE [13:0] R/W NAME R Divider Ratio W DEFLT 14 1h DESCRIPTION Local value for reference division ratio. Auxiliary SPI Registers The following two registers define the communication through the AUXSPI. If the AUXSPI is enabled (Reg 04h[4] = 0), writes to AUXSPI are executed via Reg 03h. The auxiliary device address is expected in Reg 04h[2:0]. If HMC983LP5E is working as a standalone frequency divider the AUXSPI clock is expected on the DNSAT pin, and Reg 04h[15] must be set to 1. It is recommended to disable AUXSPI when not used. Table 11. Reg 03h AUX. VCO Data Register BIT TYPE NAME W DEFLT [3:0] R/W AUXSPI Register Address 4 0h [12:4] R/W AUXSPI Data 9 000h DESCRIPTION 4-bit Register address for the auxiliary device SPI. 9-bit long Register Data for the auxiliary device SPI. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 12. Reg 04h - AUX. VCO Settings Register TYPE W DEFLT R/W Auxiliary Device Address NAME 3 000h [3] R/W Divide Clock by 4 for AUXSPI 1 0 [4] R/W Start AUXSPI 1 0 [7:5] R/W Reserved 3 4h [9:8] R/W Reserved 2 2h [13:10] R/W Reserved 4 8h [14] R/W Reserved 1 0 [15] R/W Keep Xtal Gate Open 1 0 [18:16] R/W Reserved 3 0h DESCRIPTION Chip address used by AUXSPI. 0 = Use XTAL for AUXSPI clock. 1 = Use XTAL divided by 4 for AUXSPI clock. 0 = Start AUXSPI when data is written to Reg03h. 1 = reserved. When 1, keeps the XTAL gate open to get XTAL from the companion PFD/CP chip HMC984LP4E. Table 13. Reg 05h Integer Set-Point, Trigger Delay Register BIT TYPE NAME W DEFLT Integer Division Ratio [19:0] R/W 20 200d DESCRIPTION Sigma-Delta Modulator integer set point. Specifies the integer part of the division ratio for the RF Divider in fractional mode or the integer division ration in integer mode. Also used as delay counter for hardware ramp trigger (Pin D4) in ramp mode. This value is valid when Reg 0Eh [11] = 1. Ramp Trigger Delay Table 14. Reg 06h Fractional Set-Point, Down Dwell Register (MSB) BIT TYPE NAME W DEFLT Fractional Division Ratio (MSB) [29:0] R/W Down Dwell for Asymmetric Frequency. Ramp (MSB) 30 0 DESCRIPTION Most significant 30 bits to specify fractional set point for SigmaDelta Modulator. Total Fractional bits are 48. Defines the MSB portion of the dwell down time in the asymmetric frequency sweep mode, valid when Reg 0Eh[11]=1. Table 15. Reg 07h Fractional Set-Point, Down Dwell Register (LSB) BIT TYPE NAME W DEFLT Fractional Division Ratio (LSB) [17:0] R/W Down Dwell for Asymmetric Frequency. Ramp (LSB) 18 0 DESCRIPTION Least significant 18 bits to specify fractional set point for SigmaDelta Modulator. Total Fractional bit are 48. Defines the LSB portion of the dwell down time in the asymmetric frequency sweep mode, valid when Reg0E[11]=1. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] 6 FREQUENCY DIVIDERS & DETECTORS - SMT BIT [2:0] 6 - 26 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 16. Reg 08h GPIO Configuration Register BIT TYPE NAME W DEFLT [3:0] R/W GPO Output Select 4 0h [8:4] R/W GPO Static Test Value 5 00000b Static GPIO test signals for output (D4,D3,D2,D1,D0). Writing these value and reading them back test the GPIO functionality. Master enable for GPIO Reg 01h[4] = 1 is required.. 11111b Independent GPIO pin enables. Reg08[13] = 0 - D4 input Reg08[13] = 1 - D4 output Reg08[12] = 0, D3 input Reg08[12] =1, D3 output Reg08[11] = 0, D2 input Reg08[11] = 1, D2 output Reg08[10] = 0, D1 input Reg08[10] = 1, D1 output Reg08[9] = 0, D0 input Reg08[9] = 1, D0 output Master enable for GPIO Reg 01h[4] = 1 is required. [13:9] R/W GPO Pin Enable 5 FREQUENCY DIVIDERS & DETECTORS - SMT 6 6 - 27 DESCRIPTION Selects exported output signals to GPIO pins. See Table 5 for details. Master enable for GPIO Reg 01h[4] = 1 is required.. Table 17. Reg 09h Companion Chip Address Local Register BIT TYPE NAME W DEFLT [2:0] R/W Counterpart HMC984LP4E Chip Address 3 2h DESCRIPTION Chip address of the companion chip HMC984LP4E. Table 18. Reg 0Ah Sigma Delta Modulator Seed MSB Register BIT TYPE [29:0] R/W NAME Seed MSB W DEFLT 30 4241h DESCRIPTION Most significant bits of the Seed for the 1st accumulator in Sigma-Delta Modulator. Table 19. Reg 0Bh Sigma Delta Modulator Seed LSB Register BIT [17:0] TYPE R/W NAME Seed LSB W 18 DEFLT 10081h DESCRIPTION Least significant bits of the Seed for the 1st accumulator in Sigma-Delta Modulator. Table 20. Reg 0Ch Ramp NSTEP Down MSB Register BIT TYPE [29:0] R/W NAME Down Ramp Number of Steps (MSB) W DEFLT 30 0h DESCRIPTION Most significant bits of the number of steps for the frequency ramp in down direction in sweep mode. Table 21. Reg 0Dh Ramp NSTEP Down LSB Register BIT TYPE [17:0] R/W NAME Down Ramp Number of Steps (LSB) W DEFLT 18 0h DESCRIPTION Least significant bits of the number of steps for the frequency ramp in down direction in sweep mode. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 22. Reg 0Eh Sigma Delta Modulator Configuration Register TYPE NAME W DEFLT DESCRIPTION DSM Type. 00 = MASH1 - Reserved 01 = MASH11 - Reserved 10 = MASH111 - Delta Sigma Modulator Mode B 11 - Delta Sigma Modulator Mode A [1:0] R/W SD Modulator Type 2 11b [2] R/W Ramp Auto Repeat Control from SPI 1 0 Recommended to write 1 to this bit in ramp mode. When this bit is 1, the ramp will repeat itself if ramp_auto_repeat_on/off_from_ spi is 1 at the end of the each sweep. [3] R/W Ramp Auto Repeat Control from SPI On/Off 1 0 Ramp will automatically repeat itself if this bit is 1 and bit 2 is also set to 1. Delay through the integer signal path to compensate for the fractional path. 000 = no delay. 110 = 6 clock cycles delay. 111 = Automatic. [6:4] R/W Integer Path Delay 3 111 [7] R/W Ramp Start Delay Enable 1 0 Delay the start of sweep as defined in Reg 05h Reseed when changing the frac setpoint. [8] R/W Autoseed Mode Enable 1 1 [9] R/W Reserved 1 0 [10] R/W Maintain DSM State Enable 1 0 Maintain DSM state within the same integer boundary. [11] R/W Ramp Mode Enable 1 0 Puts DSM in frequency sweeper (ramp) mode. [12] R/W Ramp Start from SPI 1 0 Start ramp signal from SPI. [13] R/W Start Ramp from Ext. Trigger 1 0 Allow external trigger to manipulate ramp. [14] R/W Bypass All 1 0 Bypass Delta Sigma Modulator. Place synthesizer in Integer Mode without disabling the DSM. [18:15] R/W CSP Step Size 4 1111b Cycle Slip Prevention (CSP) step size. In a PLL configuration with the HMC984LP4E one step is equivalent to one divided VCO cycle, and step size is the number of VCO cycles. [19] R/W External DSM Sequence Enable 1 0 Use external DSM sequence imported through GPIO Port. [20] R/W Use Falling Edge of DSM Clock for External Sequence 1 0 Use falling edge of SD clock to get the external sequence. [21] R/W Lock using External Trigger Pin 1 0 Allow external trigger to start locking process. Writing to the Integer or Fractional Division ratio registers does not have any effect when this bit is set to 1. PLL will lock only when external trigger goes high. [22] R/W Symmetrical Ramp Mode 1 1 Use symmetric frequency sweeping for up and down directions otherwise DN parameters are taken from Registers Reg 0Ch, Reg 0Dh, Reg 19h and Reg 1Ah for asymmetric mode. [23] R/W Integer Mode Lock Strobe 1 0 Re-lock when integer set-point Reg 06h is updated. [24] R/W Singlestep Ramp Mode Enable 1 0 Single-step the ramp. Each step of the ramp must be popped by strobe (either SPI or Hardware pin). [25] R/W Single Direction Ramp Mode Enable 1 0 Single direction mode for ramp (ramp one way, pop to base the other way). [26] R/W Ramp Start Direction 1 1 Starting direction of ramp. It is only loaded while rampmode = 0. 1 = Positive 0 = Negative [27] R/W Use External Clock for DSM 1 0 1 = Use external clock from GPIO pin to clock DSM. [28] R/W Reserved 1 0 [29] R/W Use x16 CSP Step 1 0 1 = Increase the CSP step size given in bits [18:15] by a factor of 16. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] 6 FREQUENCY DIVIDERS & DETECTORS - SMT BIT 6 - 28 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 23. Reg 0Fh VCO Divider Configuration Register BIT TYPE [0] R/W [1] R/W NAME W DEFLT DESCRIPTION Increase Divider Pulse width to DSM 1 0 Increase the width of the clock pulse going to DSM (available only when division ratio > 64). Increase Divider Pulsewidth to PFD 1 1 Increase pulse width (low duration) of the clock going to PFD. Sets current for divider output buffer. Helps to control voltage swing for various impedance options. 000 = 5mA 001 = 7.5mA [4:2] R/W Output Buffer Current Select 2 011b 010 = 10mA 011 = 12.5mA 100 = 10mA 6 101 = 12.5mA 110 = 15mA FREQUENCY DIVIDERS & DETECTORS - SMT 111 = 17.5mA 6 - 29 [5] R/W Reset RF Divider 1 0 Resets the RF Divider. [8:6] R/W Divider Resynch Bias Select 3 011b Bias current setting for divider resync. Default value recommended. [11:9] R/W RF Buffer Bias Select 3 001b Bias current setting for input RF buffer. Default value recommended. Divider output pulse width control. 000 = 5 VCO cycles. 001 = 13 VCO cycles. 010 = 21 VCO cycles. [14:12] R/W Divider Pulsewidth Select 3 011b 011 = 29 VCO cycles. 100 = 37 VCO cycles. 101 = 45 VCO cycles. 110 = 53 VCO cycles. 111 = 61 VCO cycles. Table 24. Reg 10h Ramp DWELL Symmetrical or Up MSB Register BIT [29:0] TYPE R/W NAME Symmetric Ramp Dwell (MSB) W 30 DEFLT DESCRIPTION 0 Represents MSB’s for ramp dwell time in up and down directions for symmetric frequency sweep mode. In asymmetric mode it represents the up dwell time only. Table 25. Reg 11h Ramp DWELL Symmetrical or Up LSB Register BIT [17:0] TYPE R/W NAME Symmetric Ramp Dwell (LSB) W 18 DEFLT DESCRIPTION 0 Represents LSB’s for ramp dwell time in up and down directions for symmetric frequency sweep mode. In asymmetric mode it represents the up dwell time only. Table 26. Reg 12h Ramp Step Size Symmetrical or Up MSB Register BIT [29:0] TYPE R/W NAME Symmetric Ramp Step Size (MSB) W 30 DEFLT 0 DESCRIPTION Represents the MSB for ramp step size in up and down directions for symmetric frequency sweep mode. In asymmetric mode it represents the up step size only. For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 27. Reg 13h Ramp Step Size Symmetrical or Up LSB Register BIT [17:0] TYPE R/W NAME Symmetric Ramp Step Size (LSB) W DEFLT DESCRIPTION 0 Represents the LSB for ramp step size in up and down directions for symmetric frequency sweep mode. In asymmetric mode it represents the up step size only. 18 Table 28. Reg 14h Ramp NSTEP Symmetrical or Up MSB Register [29:0] TYPE R/W NAME Symmetric Ramp Number of Steps (MSB) W DEFLT 30 0 DESCRIPTION Represents the MSB of the number of steps for the frequency ramp in up and down directions in symmetric frequency sweep mode. In asymmetric mode it represents the number of steps in up direction only. Table 29. Reg 15h Ramp NSTEP Symmetrical or Up LSB Register BIT [17:0] TYPE R/W NAME W Symmetric Ramp Number of Steps (LSB) DEFLT 18 0 DESCRIPTION Represents the LSB of the number of steps for the frequency ramp in up and down directions in symmetric frequency sweep mode. In asymmetric mode it represents the number of steps in up direction only. Table 30. Reg 16h DSM Configuration Register BIT [1:0] [3:2] TYPE R/W R/W NAME W DSM 1st Accumulator Size DEFLT 2 DSM 2nd Accumulator Size 2 DESCRIPTION 00b DSM 1st accumulator width. 00 = 48 bits 01 = 32 bits 10 = 24 bits 11 = 16 bits 00b DSM 2nd accumulator width. 00 = 48 bits 01 = 32 bits 10 = 24 bits 11 = 16 bits [5:4] R/W DSM 3rd Accumulator Size 2 00b DSM 3rd accumulator width. 00 = 48 bits 01 = 32 bits 10 = 24 bits 11 = 16 bits [8:6] R/W Disable Frac. Register Clock 3 000b Clock gates for the 3 accumulators (fractional part), 1 disables the clock. [11:9] R/W Disable Integer Register Clock 3 000b Clock gates for the 3 accumulators (integer part), 1 disables the clock. [12] R/W Disable DSM Mode A Clock 1 0 1 = Disable Delta Sigma Modulator Mode A Clock [13] R/W Disable DSM Mode B Clock 1 0 1 = Disable Delta Sigma Modulator Mode B Clock [14] R/W Reserved 1 0 [15] R/W Disable Integer Path Clock 1 0 1 = Disables Integer Path Clock [16] R/W Disable Input Buffer Clock 1 0 1 = Disables Input Buffer Clock [17] R/W Disable Output Buffer Clock 1 0 1 = Disables Output Buffer Clock [18] R/W Reserved 1 0 [19] R/W Reserved 1 0 For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] 6 FREQUENCY DIVIDERS & DETECTORS - SMT BIT 6 - 30 HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER Table 31. Reg 17h This Register does not exist BIT TYPE NAME W DEFLT DESCRIPTION This Register does not exist Table 32. Reg 19h Ramp Down Step Size MSB Register TYPE [29:0] R/W NAME Ramp Step Down MSB. W DEFLT 30 0 DESCRIPTION Represents MSB’s to define the step size for the ramp in down direction in ramp mode. Table 33. Reg 1Ah Ramp Down Step Size LSB Register BIT [17:0] TYPE R/W NAME Ramp Step Down LSB. W 18 DEFLT 0 DESCRIPTION Represents LSB’s to define the step size for the ramp in down direction in ramp mode. FREQUENCY DIVIDERS & DETECTORS - SMT 6 BIT 6 - 31 For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] HMC983LP5E v00.0911 DC - 7 GHZ FRACTIONAL-N DIVIDER AND FREQUENCY SWEEPER NOTES: FREQUENCY DIVIDERS & DETECTORS - SMT 6 For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824 978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com Application Support: [email protected] 6 - 32