DATA SHEET SKY12349-362LF: 0.7-4.0 GHz Five-Bit Digital Attenuator with Serial-to-Parallel Driver (0.5 dB LSB) Applications • Base stations • Wireless and RF data • Wireless local loop gain control circuits Features • Broadband operation: 0.7 to 4.0 GHz • Attenuation: 15.5 dB • LSB attenuation: 0.5 dB • Low insertion loss: 1 dB @ 900 MHz • Positive voltage operation: 5 V • Integrated silicon serial-to-parallel driver • Small, QFN (24-pin, 4 x 4 mm) package (MSL1, 260 °C per JEDEC J-STD-020) Figure 1. SKY12349-362LF Block Diagram Description The SKY12349-362LF is a GaAs FET five-bit digital attenuator I/C with a serial-to-parallel driver. The device is provided in a 4 x 4 mm, 24-pin Quad Flat No-Lead (QFN) package. The SKY12349-362LF is particularly suited for applications in which high attenuation accuracy, low insertion loss, and low intermodulation products are required. A functional block diagram is shown in Figure 1. The pin configuration and package are shown in Figure 2. Signal pin assignments and functional pin descriptions are provided in Table 1. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201399B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • April 11, 2011 1 DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Figure 2. SKY12349-362LF Pinout – 24-Pin QFN (Top View) Table 1. SKY12349-362LF Signal Descriptions Pin # Name Description Pin # Name Description 1 GND or N/C Ground or no connection 13 GND or N/C Ground or no connection 2 RF1 RF input/output. Must be DC blocked. 14 VCC Fixed bias for SPI 3 GND or N/C Ground or no connection 15 GND or N/C Ground or no connection 4 GND or N/C Ground or no connection 16 GND or N/C Ground or no connection 5 SERIAL_OUTPUT Data output delayed by eight clock cycles 17 RF2 RF input/output. Must be DC blocked. 6 GND or N/C Ground or no connection 18 GND or N/C Ground or no connection 7 RESET Reset. Clears shift registers. 19 GND Ground 8 CLOCK Serial clock input 20 GND Ground 9 LATCH_ENABLE On rising edge of pulse, shifts five most recent clocked-in bits to set attenuation state 21 GND Ground 10 GND or N/C Ground or no connection 22 GND Ground 11 SERIAL_INPUT Data input 23 GND Ground 12 GND or N/C Ground or no connection 24 GND Ground Note: Exposed pad must be grounded. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 2 April 11, 2011 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201399B DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Functional Description The SKY12349-362LF is a five bit digital attenuator comprised of a GaAs attenuator and a silicon CMOS driver. The attenuation setting is controlled by a serial-to-parallel interface. Attenuation is set by a stream of data that is clocked into the shift registers of the silicon chip by the clock signal. To set the attenuation state, a latch signal is sent to the appropriate pin to send the correct bias voltages to the GaAs attenuator. More than one attenuator can be cascaded together and the data may be passed through one device to the other using the SERIAL_OUTPUT signal (pin 5). To reset the attenuator to the insertion loss state, a logic low signal may be sent to the RESET pin. DC bias voltage to the silicon CMOS chip is applied to pin 14 (VCC). Power-Up/Power-Down Timing Serial input data (SERIAL_INPUT pin) is shifted into the register on the rising edge of the clock (CLOCK pin), least significant bit (LSB) first. The attenuator changes states on the rising edge of the latch-enable (LATCH_ENABLE pin) signal, according to the most recent five bits of shifted data accepted since the previous falling edge of the latch enable signal. The serial data output is the serial input data delayed by eight clock cycles. Refer to the timing diagram in Figure 3 and timing parameter specifications in Table 2. Table 3 shows the transition states based on the latch enable, clock, and reset logic settings. Power-up sequence is as follows: 0. Connect ground 1. Apply VCC 2. Set all inputs (SCK, SDA, LE) The power-down sequence is the reverse of above. Figure 4 shows an example of how to set the attenuator to the 0.5 dB state. The progression of the bit states vs the clock signal is shown. The timing diagram shows that when the latch enable signal goes high, the voltages v1 to v5 set the attenuator to the 0.5 dB state. Electrical and Mechanical Specifications The absolute maximum ratings of the SKY12349-362LF are provided in Table 4. Electrical specifications are provided in Tables 5 and 6. Typical performance characteristics of the SKY12349-362LF are illustrated in Figures 5 through 11. The state of the SKY12349-362LF is determined by the logic provided in Table 7. Figure 3. Power-Up/Power-Down Timing Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201399B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • April 11, 2011 3 DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Table 2. Power-Up/Power-Down Timing Parameters Parameter Symbol VCC = 5 V Minimum VCC = 3 V Typical Maximum Minimum Typical Maximum Units Serial input setup time ts 5 5 ns Hold time from serial input to shift clock th 5 5 ns Setup time from shift clock to latch enable tlsup Propagation delay, latch enable to C0.5 through C8 tpd Setup time from reset to shift clock – Clock frequency fCLK 40 100 ns 30 20 70 ns 10 MHz 50 ns 30 Table 3. Transition State Logic LATCH_ENABLE (Pin 9) CLOCK (Pin 8) RESET (Pin 7) X X L H Shift register clocked X H Contents of shift register transferred to digital attenuator X Function Shift register cleared Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 4 April 11, 2011 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201399B DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Figure 4. Example for Setting 0.5 dB State Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201399B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • April 11, 2011 5 DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Table 4. SKY12349-362LF Absolute Maximum Ratings Parameter Symbol Minimum Maximum Units +30 dBm RF input power @ 5 V PIN Supply voltage VCC 6 V Control voltage VCTL –0.2 +8 V Operating temperature TOP –40 +85 °C Storage temperature TSTG –65 +150 °C Note: Exposure to maximum rating conditions for extended periods may reduce device reliability. There is no damage to device with only one parameter set at the limit and all other parameters set at or below their nominal value. Exceeding any of the limits listed here may result in permanent damage to the device. CAUTION: Although this device is designed to be as robust as possible, Electrostatic Discharge (ESD) can damage this device. This device must be protected at all times from ESD. Static charges may easily produce potentials of several kilovolts on the human body or equipment, which can discharge without detection. Industry-standard ESD precautions should be used at all times. Table 5. SKY12349-362LF Electrical Specifications (1 of 2) (Note 1) (VCC = 3 to 5 V, VCTL = 0 to 3 V and 5 V, TOP = +25 °C, PIN = 0 dBm, Characteristic Impedance [ZO] = 50 Ω, , Unless Otherwise Noted) Parameter Insertion loss Symbol Test Condition Min 0.7 to 1.4 GHz 1.4 to 2.3 GHz 2.3 to 2.7 GHz 2.7 to 4.0 GHz Attenuation range Attenuation accuracy Max Units 1.2 1.3 1.8 2.0 1.5 2.0 2.3 2.7 dB dB dB dB 15.5 dB ±(0.5 + 5% of attenuation setting max) ±(0.3 + 4% of attenuation setting max) ±(0.5 + 5% of attenuation setting max) dB dB dB 15 17 15 12 17 20 17 13 dB dB dB dB 50% VCTL to 90% RF or 10/90% RF 1200 ns 50% VCTL to 10% RF or 90/10% RF 500 ns Attenuation referred to insertion loss, all attenuation states 0.7 to 0.9 GHz 0.9 to 2.2 GHz 2.2 to 4.0 GHz Return loss RF1 and RF2 pins, all attenuation states 0.7 to 1.4 GHz 1.4 to 2.3 GHz 2.3 to 2.7 GHz 2.7 to 4.0 GHz Switching characteristics: On/rise time Off/fall time Typical Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 6 April 11, 2011 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201399B DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Table 5. SKY12349-362LF Electrical Specifications (2 of 2) (Note 1) (VCC = 3 to 5 V, VCTL = 0 to 3 V and 5 V, TOP = +25 °C, PIN = 0 dBm, Characteristic Impedance [ZO] = 50 Ω, Unless Otherwise Noted) Parameter Symbol Input power for 0.1 dB compression Test Condition Min Max Units 0.7 to 3.8 GHz VCC = VCTL = 5 V VCC = VCTL = 3 V Input power for 1 dB compression +25 +23 dBm dBm +32 +30 dBm dBm +42 +42 dBm dBm 0.7 to 3.8 GHz VCC = VCTL = 5 V VCC = VCTL = 3 V 3rd Order Input Intercept Point Typical IIP3 0.7 to 3.8 GHz, for twotone input power. 0 dBm/tone, 1 MHz spacing VCC = VCTL = 5 V VCC = VCTL = 3 V Note 1: Performance is guaranteed only under the conditions listed in this Table and is not guaranteed over the full operating or storage temperature ranges. Operation at elevated temperatures may reduce reliability of the device. Table 6. DC Electrical Characteristics (Note 1) (VCC = 3 to 5 V, VCTL = 0 to 3 V and 5 V, TOP = +25 °C, PIN = 0 dBm, Characteristic Impedance [ZO] = 50 Ω, , Unless Otherwise Noted) Parameter Symbol Test Condition Min Typical Max Units Input voltage, high VIH VCC = 3 V VCC = 5 V 2.3 3.0 3.0 5.0 V V Input voltage, low VIL VCC = 3 V VCC = 5 V 0 0 1.0 1.5 V V Input leakage current IL Quiescent current ICC Supply voltage VCC μA 0.5 μA 500 3.0 5.0 5.5 V Note 1: Performance is guaranteed only under the conditions listed in this Table and is not guaranteed over the full operating or storage temperature ranges. Operation at elevated temperatures may reduce reliability of the device. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201399B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • April 11, 2011 7 DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Typical Performance Characteristics (VCC = 5 V, VCTL = 0 to 5 V, TOP = +25 °C, PIN = 0 dBm, CBLK = 47 pF, Characteristic Impedance [ZO] = 50 Ω, Unless Otherwise Noted) Figure 5. Insertion Loss vs Frequency Figure 6. Input Return Loss: Major States Figure 7. Normalized Attenuation: Major States Figure 8. Attenuation Bit Error vs Attenuation State Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 8 April 11, 2011 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201399B DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Figure 10. Relative Phase: Major States Figure 9. Attenuation Bit Error: Major States Figure 11. Worst Case Attenuation Step Error Between Successive Attenuation States Table 7. SKY12349-362LF Truth Table RF1/RF2 (Pins 2 & 17) Attenuation Serial Data Input RESET (Pin 7) 0.5 dB 1.0 dB 2.0 dB 4.0 dB 8.0 dB Insertion loss 1 1 1 1 1 1 0.5 dB 1 0 1 1 1 1 1.0 dB 1 1 0 1 1 1 2.0 dB 1 1 1 0 1 1 4.0 dB 1 1 1 1 0 1 8.0 dB 1 1 1 1 1 0 15.5 dB 1 0 0 0 0 0 Insertion loss 0 X X X X X Note: For VCC = 5 V: “1” = VIH = +3.0 V to +5 V. “0” = VIL = 0 to +1.5 V. For VCC = 3 V: “1” = VIH = +2.3 V to +3 V. “0” = VIL = 0 to +1.0 V. “X” = don’t care. This Table shows the logic required for the major bits and full attenuation. Bit states need to be used in combination to set the sum of the bits selected. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201399B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • April 11, 2011 9 DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Evaluation Board Description Package and Handling Information The SKY12349-362LF Evaluation Board is used to test the performance of the SKY12349-362LF digital attenuator. An assembly drawing for the Evaluation Board is shown in Figure 12 and an Evaluation Board schematic diagram is shown in Figure 13. Instructions on the shipping container label regarding exposure to moisture after the container seal is broken must be followed. Otherwise, problems related to moisture absorption may occur when the part is subjected to high temperature during solder assembly. Package Dimensions THE SKY12349-362LF is rated to Moisture Sensitivity Level 1 (MSL1) at 260 °C. It can be used for lead or lead-free soldering. For additional information, refer to the Skyworks Application Note, Solder Reflow Information, document number 200164. The PCB layout footprint for the SKY12349-362LF is shown in Figure 14. Typical case markings are noted in Figure 15. Package dimensions for the 24-pin QFN are shown in Figure 16, and tape and reel dimensions are provided in Figure 17. Care must be taken when attaching this product, whether it is done manually or in a production solder reflow environment. Production quantities of this product are shipped in a standard tape and reel format. Figure 12. SKY12349-362LF Evaluation Board Assembly Diagram Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 10 April 11, 2011 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201399B DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Figure 13. SKY12349-362LF Evaluation Board Schematic Diagram Figure 14. SKY12349-362LF PCB Layout Footprint Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201399B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • April 11, 2011 11 DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Figure 15. Typical Part Markings Figure 16. SKY12349-362LF 24-Pin QFN Package Dimensions Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 12 April 11, 2011 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201399B DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Figure 17. SKY12349-362LF Tape and Reel Dimensions Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201399B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • April 11, 2011 13 DATA SHEET • SKY12349-362LF FIVE-BIT DIGITAL ATTENUATOR Ordering Information Model Name SKY12349-362LF Digital Attenuator Manufacturing Part Number SKY12349-362LF Evaluation Board Part Numbers SKY12349-362LF-EVB Copyright © 2011 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. 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