RF2908 11 915MHZ SPREAD SPECTRUM RECEIVER WITH PLL FREQUENCY SYNTHESIZER Typical Applications • Digital Cordless Telephones • Inventory Tracking • Secure Communication Links • Wireless Security • Wireless LANs • Battery Powered Applications Product Description The RF2908 is a monolithic integrated circuit specifically designed for direct-sequence spread-spectrum systems operating in the 902MHz to 928MHz ISM band. The part includes a direct conversion receiver, quadrature demodulator, dual IF amplifiers with gain control and RSSI, onchip programmable baseband filters, dual data comparators, and a serially programmable 86-channel PLL frequency synthesizer. Two cell or regulated three cell (3.6V maximum) battery applications are supported by the part. The part is also designed to operate in compliance with FCC Part 15.247. The device is provided in 48-lead plastic LQFP packaging. .362 .346 .020 .362 .346 .280 .272 .280 .272 Optimum Technology Matching® Applied üSi Bi-CMOS GaAs HBT GaAs MESFET SiGe HBT Si CMOS .011 .007 .057 .053 7°MAX 0°MIN .031 .021 Si BJT .006 .002 .007 MAX Package Style: LQFP-48 11 Features 1,2 LNA IN Q± TRANSCEIVERS • FCC Part 15.247 Compliant MOUT Q± • Direct Conversion Receiver 47,48 IF Amp Q Data Amp LNA IN 6 39 Q DATA • On-Chip 86 Channel Frequency Synthesizer +45° -45° 42 IF OUT Q RSSI Gain Control 19 IF OUT I PLL Freq. Synth. 21 I DATA IF Amp 23 24 11,12 13,14 MOUT I± IN I± • 2.7V to 3.6V Operation I Data Amp Ref Refer to the Detailed Functional Block Diagram for description of full functionality Functional Block Diagram Rev C1 010904 • On-Chip Selectable IF Bandwidths Ordering Information RF2908 915MHz Spread Spectrum Receiver with PLL Frequency Synthesizer RF Micro Devices, Inc. 7628 Thorndike Road Greensboro, NC 27409, USA Tel (336) 664 1233 Fax (336) 664 0454 http://www.rfmd.com 11-85 RF2908 Absolute Maximum Ratings Parameter Ratings Unit Supply Voltage Control Voltages Input RF Level Output Load VSWR Operating Ambient Temperature Storage Temperature -0.5 to +3.6 -0.5 to +3.6 +20 50:1 -40 to +85 -40 to +150 VDC VDC dBm Parameter °C °C Caution! ESD sensitive device. RF Micro Devices believes the furnished information is correct and accurate at the time of this printing. However, RF Micro Devices reserves the right to make changes to its products without notice. RF Micro Devices does not assume responsibility for the use of the described product(s). Specification Min. Typ. Max. Unit 902 to 928 100 6.0 -12 +5.5 -100 -65 0.35 to 3.1 30 65 MHz dB dB dBm dBm dBm dBm V mV/dB dB T=25 °C, VCC =3.6V, Freq=915MHz Overall Frequency Range Cascaded Voltage Gain Cascaded Noise Figure Cascaded Input IP3 RX Sensitivity LO Leakage RSSI DC Output Range RSSI Sensitivity RSSI Dynamic Range Condition 60 8.0 High Gain Low Gain IF BW =960kHz, Freq=915MHz, S/N=8dB At LNA IN RLOAD =51kΩ LNA and Mixer Operating Frequency Range Voltage Gain Noise Figure RF Input Impedance RF Input VSWR Input IP3 TRANSCEIVERS 11 902 to 928 22 6.0 50 2:1 -20 Quadrature Phase Balance Quadrature Amplitude Balance Mixer Output Impedance DC Current Consumption 11-86 8.0 MHz dB dB Ω 150 26 -12 +5.5 ±3 ±5 dBm dBm ° ±1 200 33 250 39 dB Ω mA At maximum gain. ATTN=LOW At minimum gain. ATTN=HIGH With expected LO amplitude and harmonic content. Differential Operating at a 3.3V supply voltage. Rev C1 010904 RF2908 Parameter Specification Min. Typ. Max. Unit Condition IF and Data Amplifiers IF Frequency Range Voltage Gain Noise Figure Note 1 77 Input IP3 Output DC Offset Gain Control Range Gain Control Voltage Range Gain Control Sensitivity VGA Output Voltage VGA DC Output Voltage Output P1dB RSSI Range RSSI Output Voltage Compliance Input Impedance 65 1.2 80 5 35 -65 +2 0 70 25 2.0 55 -0.08 500 1.7 1.64 60 0.5 to 2.4 1.5 2 1 9.6 83 2.5 MHz dB dB dB dBm dBm mV dB V dB/mV mVPP V VPP dB V kΩ At maximum gain setting At minimum gain setting At maximum gain setting At minimum gain setting Driving a 5kΩ load At maximum gain setting Maximum RSSI is 2.5V or VCC -0.3, whichever is less. Differential Note 1. The lower cutoff frequency is a function of: a) input DC blocking cap size; b) DC feedback capacitor; and, c) gain setting. But, recommended component values will yield a cutoff of <10kHz. Filters Five pole Bessel Bandwidth 1, 2, 4, 8 Passband Ripple Group Delay Ultimate Rejection MHz 1 100 80 dB ns 100 dB 100 dB MHz ns V Five pole Bessel internal LPF. Three pole external LPF. Selectable from 1, 2, 4, and 8MHz. Refer to “IF Bandwidth Response” chart. At 8MHz, increasing as bandwidth decreases. 11 Data Amplifiers Voltage Gain Bandwidth Rise and Fall Time Logic High Output 10 2 5 VCC -0.3V Logic Low Output 0.3 V Can sink/source 1mA and maintain these logic levels. Can sink/source 1mA and maintain these logic levels. PLL, Synthesizer, VCO and LO VCO Tuning Range VCO Sensitivity Charge Pump Current Reference Frequency Crystal Reference Crystal Rs Phase Noise LO Output Level Lock Time Step Size Rev C1 010904 20 800 to 1200 30 100 9.6 60 -66 -96 -10 1.5 300 40 20 80 MHz MHz/V µA MHz Ω dBc/Hz dBc/Hz dBm ms kHz Determined by external resistor. KPD =100µA/2π=0.0159ma/2π rad 10kHz offset. 100kHz offset. Into 100Ω differential load From sleep mode. 86 channels in the 902MHz to 928MHz ISM band. 11-87 TRANSCEIVERS Characteristics RF2908 Parameter Specification Min. Typ. Max. Unit Condition Power Down Control Logical Controls “ON” Logical Controls “OFF” Control Input Impedance Turn On Time VCC -0.3V VCC +0.3V V Voltage supplied to the input 0.3 V MΩ ms Voltage supplied to the input >1 1 1 ms 100 µs 0 Turn Off Time RX to TX and TX to RX Time Reference Crystal=9.6MHz. Dependent on reference crystal. Higher frequencies reduce turn on/off times. Reference Crystal=9.6MHz. Dependent on reference crystal. Higher frequencies reduce turn on/off times. Power Supply Voltage Current Consumption 2.7 3.3 50 3.6 62 V mA 50 45 57 µA mA VCC =3.3V; RX ENABL=HIGH; PLL ENABL=HIGH VCC =3.3V; Sleep Mode VCC =3.3V; RX ENABL=LOW; PLL ENABL=HIGH TRANSCEIVERS 11 11-88 Rev C1 010904 RF2908 Function MOUT Q- 2 3 4 5 6 7 8 9 10 MOUT Q+ MIX VCC MIX GND LNA GND LNA IN SW GND LNA VCC SW GND2 ATTN 11 12 MOUT I+ MOUT I- 13 14 15 16 17 IN I+ IN IGND2 DCFB I VCC2 18 19 20 21 GND3 IF OUT I VCC3 I DATA 22 23 RSSI I OSC B 24 OSC E 25 LE 26 PLL CLK 27 PLL DATA 28 29 30 31 PLL GND PLLD VCC LO OUT B RESNTR+ 32 33 34 RESNTRLO OUT DO Rev C1 010904 Description Interface Schematic The complementary quadrature phase signal output from the front-end mixer. See pin 2. The quadrature phase signal output from the front-end mixer. Supply voltage for the front-end quadrature mixers. Ground connection for the front-end quadrature mixers. Ground connection for the low noise amplifier (LNA). Input to the attenuator and LNA. Ground connection for the input attenuator. Supply voltage for the LNA. Ground connection for the input attenuator. Input attenuator control point. When connected “high”, the attenuator adds 20dB of series attenuation. When connected “low”, the attenuator adds 0dB of series attenuation. The in-phase signal output from the front-end mixer. The complementary in-phase signal output from the front-end mixer. See pin 12. Input for the in-phase IF channel. Complementary input for the in-phase IF channel. Ground for VCC2. DC feedback capacitor for in-phase channel. Power supply for VGA amplifier 3, differential to single-ended converter, and post filter. Ground for VCC3. Analog signal IF output for in-phase channel. Power supply for data amplifier. Logic-level data output for the in-phase channel. This is a digital output signal obtained from the output of a Schmitt trigger. Received signal strength indicator for the in-phase channel. 11 Base connection point for external reference crystal. The reference crystal is connected between this pin and ground. Emitter connection point for external reference crystal. Feedback capacitors are connected between this pin and ground. Latches data entered into the serial port. Data is clocked into the latch on the rising edge of LE. See table and timing diagram. PLL shift register clock. The rising edges of this clocking signal load in the serial data present at the PLL DATA input pin into the internal latch. See table and timing diagram. Input data for loading the counters. Clocked, serial data at this port is presented to the shift register, then to the latch, and finally to the counter. Each clock transition sends a single bit to the on-board 7-bit shift register. The MSB is loaded first. See table and timing diagram. Ground connection for the PLL. TRANSCEIVERS Pin 1 Supply voltage for the PLL. Complementary local oscillator output. See pin 33. This port is used to supply DC voltage to the VCO as well as tune the center frequency of the VCO. This is the complementary port to pin 31. Refer to pin 31. Local oscillator output. Connection point for the loop filter. 11-89 RF2908 Pin 35 Function Description PLL ENABL This pin is used to power up or down the VCO and PLL. A logic high 36 RX ENABL 37 BW SEL2 38 BW SEL1 39 Q DATA 40 41 42 43 44 RSSI Q VREF IF OUT Q VGC VCC1 45 46 47 48 DCFB Q GND1 IN QIN Q+ Interface Schematic (PLL ENABL>2.0V) powers up the VCO and PLL circuitry. A logic low (PLL ENABL<1.0V) powers down the PLL and VCO. Enable pin for the receiver circuits. RX ENABL>2.0V powers up all receiver functions. RX ENABL<1.0V turns off all receiver functions except the PLL functions and the RF mixer. Bandwidth select logic input. Pin 37 and pin 38 provide a two bit control word for the setting of the IF bandwidth. See Table1. Bandwidth select logic input. Pin 37 and pin 38 provide a two bit control word for the setting of the IF bandwidth. See Table1. Logic-level data output for the quadrature channel. This is a digital output signal obtained from the output of a Schmitt trigger. Received signal strength indicator for the quadrature channel. Gain control reference voltage. Analog signal IF output for quadrature channel. Gain control voltage. Power supply for bias circuits and VGA amplifiers for both the in-phase and quadrature channels. DC feedback capacitor for quadrature channel. Ground for VCC1 for both the in-phase and quadrature channels. Minus input for quadrature channel Plus input for quadrature channel Table 1: Bandwidth Selection Controls BWSEL1 BWSEL2 0 0 1 1 0 1 0 1 TRANSCEIVERS 11 11-90 IF-3dB Frequency 1MHz 2MHz 4MHz 8MHz Rev C1 010904 RF2908 Table 2: Channel Plan Data f, MHz Data f, MHz Data f, MHz Data f, MHz 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 902.4 * 903 903.3 903.6 903.9 904.2 904.5 904.8 905.1 905.4 905.7 906 906.3 906.6 906.9 907.2 907.5 907.8 908.1 908.4 908.7 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 909 909.3 909.6 909.9 910.2 910.5 910.8 911.1 911.4 911.7 912 912.3 912.6 912.9 913.2 913.5 913.8 914.1 914.4 914.7 915 915.3 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 915.6 915.9 916.2 916.5 916.8 917.1 917.4 917.7 918 918.3 918.6 918.9 919.2 919.5 919.8 920.1 920.4 920.7 921 921.3 921.6 921.9 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 922.2 922.5 922.8 923.1 923.4 923.7 924 924.3 924.6 924.9 925.2 925.5 925.8 926.1 926.4 926.7 927 927.3 927.6 927.9 *Data 1 is invalid. Timing Diagram 11 H L 0 0 1 0 1 MSB ... 0 LSB TRANSCEIVERS 0 DATA H ... CLK L tCWH tCWL tCS tCH tES tEW H ... LE L Minimum Times: tCWH tCWL tEW tES tCS tCH Rev C1 010904 = 143 ns = 143 ns = 74 ns = 143 ns = 36 ns = 36 ns 0 time Example: Load Sequence for Channel #10 (905.4 MHz) t Decimal 10 = 0 0 0 1 0 1 0 Binary MSB LSB 11-91 RF2908 Differential Filter Design Information Butterworth Response L RS C1 C2 L RS RL RL 12 12 1 1 C1bw ⋅ --- ⋅ 10 C2bw ⋅ --- ⋅ 10 6 2 2 Lbw ⋅ RL ⋅ 10 C1 = -------------------------------------- ;C2 = -------------------------------------- ;L = ----------------------------------2 ⋅ π ⋅ fc ⋅ RL 2 ⋅ π ⋅ fc ⋅ RL 2 ⋅ π ⋅ fc C1bw = 4.5325 ;C2bw = 13.5691 ;Lbw = 0.1743 RS RS = 125 ;RL = 1000 ;------- = 0.125 RL Differential LC Filter Component Values (Butterworth Response) 100000 TRANSCEIVERS 11 Component Value 10000 1000 C2 (pF) 100 C1 (pF) 10 L (µH) 1 1.E+05 1.E+06 1.E+07 Frequency 11-92 Rev C1 010904 RF2908 Differential Filter Design Information (Cont.) Bessel Response L RS C1 C2 L RS RL RL 12 12 1 1 C1bw ⋅ --- ⋅ 10 C2bw ⋅ --- ⋅ 10 6 2 2 Lbw ⋅ RL ⋅ 10 C1 = -------------------------------------- ;C2 = -------------------------------------- ;L = ----------------------------------2 ⋅ π ⋅ fc ⋅ RL 2 ⋅ π ⋅ fc ⋅ RL 2 ⋅ π ⋅ fc C1bw = 2.6163 ;C2bw = 13.6373 ;Lbw = 0.1083 RS RS = 125 ;RL = 1000 ;------- = 0.125 RL Differential LC Filter Component Values (Bessel Response) 100000 TRANSCEIVERS 11 Component Value 10000 1000 C2 (pF) 100 C1 (pF) 10 L (µH) 1 1.E+05 1.E+06 1.E+07 Frequency Rev C1 010904 11-93 RF2908 IN Q- GND1 DCFB Q VCC1 VGC IF OUT Q VREF RSSI Q Q DATA BW SEL1 BW SEL2 48 47 46 45 44 43 42 41 40 39 38 37 LNA GND 5 32 RESNTR- LNA IN 6 31 RESNTR+ SW GND 7 30 LO OUT B LNA VCC 8 29 PLLD VCC SW GND2 9 28 PLL GND ATTN 10 27 PLL DATA MOUT I+ 11 26 PLL CLK MOUT I- 12 25 LE 13 14 15 16 17 18 19 20 21 22 23 24 OSC E 33 LO OUT OSC B 4 RSSI I MIX GND I DATA 34 DO VCC3 3 IF OUT I MIX VCC GND3 35 PLL ENABL VCC2 2 DCFB I MOUT Q+ GND2 36 RX ENABL IN I- 1 IN I+ MOUT Q- TRANSCEIVERS 11 IN Q+ Pin Out 11-94 Rev C1 010904 RF2908 ATTN LNA VCC MIX VCC MOUT Q- MOUT Q+ IN Q+ IN Q- VCC1 VCC2 VCC3 Detailed Functional Block Diagram 10 8 4 1 2 48 47 44 17 20 LNA 39 Q DATA LNA IN 6 0-25 dB SW GND1 7 0-20 dB -12-+12 17dB 42 IF OUT Q 6 dB -0.5/-20.5 45 DCFB Q +45° -45° SW GND2 9 22 RSSI I 41 VREF LNA GND 5 40 RSSI Q PLL ON 35 RX ENABL 36 BW SEL2 37 43 VGC Chip Control 21 I DATA BW SEL1 38 MIX VCC 3 19 IF OUT I MOUT I+ 11 18 GND3 MOUT I- 12 16 DCFB I Phase Detector Charge Pump IN I+ 13 IN I- 14 OSC B 23 Ref. Osc. 15 GND2 46 GND1 34 DO 300 kHz 300 kHz 5-bit Counter /32 7-Bit Counter /94 OSC E 24 32 33 28 29 PLLD GND PLLD VCC 7 7-Bit Latch 7 7-Bit Shift Register 26 PLL CLK 25 LE 27 PLL DATA 11 TRANSCEIVERS LO OUT 30 31 LO OUT B VCO RESNTR+ 902-928 MHz RESNTR- Prescaler 32/33 7-Bit Swallow Counter 0-85 Rev C1 010904 11-95 RF2908 Application Schematic 915MHz +3.3V REG Refer to Filter Design Information for Component Values L +3.3V REG 10Ω C 10Ω 0.01µF 0.01µF C L 0.1µF 47pF +3.3V REG +3.3V REG +3.3V REG 10Ω 10Ω 10Ω 0.1µF 47pF 0.1µF 10 8 3 1 2 47 48 47pF 0.1µF 44 47pF 17 0.1µF 39 LNA 6.8nH 47pF 20 6 0-25 dB 7 42 0.27µF 6 dB 45 22 5 41 40 37 56pF 43 Chip Control 21 4 19 11 18 12 16 C 0.1µF L 56pF 1µF 38 L C 17dB 35 36 0.1µF -12-12dB +45° -45° 9 Refer to Filter Design Information for Component Values 0-20 dB -0.5/-20.5 Phase Detector Charge Pump 13 14 Ref. Osc. 100pF 300 kHz 5-bit Counter /32 7-Bit Counter /94 24 100pF 15 46 34 300 kHz 23 902-928 MHz 30 31 32 11 7-Bit Swallow Counter 0-85 7 7-Bit Latch 7 7-Bit Shift Register 33 28 26 25 27 Prescaler 32/33 VCO 0.27µF 29 0.1µF 6.8nH TRANSCEIVERS 6.8nH 47pF 2kΩ 10Ω 0.1µF 4.7µF 220pF 22kΩ Loop Filter 2.2nF 47pF +3.3V REG 11-96 Rev C1 010904 RF2908 Evaluation Board Schematic (Download Bill of Materials from www.rfmd.com.) J8 IF OUT Q GC IF VCC VREF C46 1 µF C21 47 nF C22 220 nF C44 68 pF DCFBQ Q RSSI J7 Q DATA C23 100 nF L8 10 µH BW SEL1 46 45 44 43 42 41 40 39 38 37 VGC VREF RSSI Q Q DATA BW SEL1 BW SEL2 RX 36 ENBL 1 MOUT Q2 MOUT Q+ C40 10 nF VCC R6 10 Ω J1 RF IN 47 IF OUT Q C41 10 nF VCC1 T2 5:1 GND1 C42 10 pF C24 100 nF 48 DCFB Q 50 Ω µstrip RX ENABL PLL ENABL L9 10 µH IN Q- J9 Q MIX OUT BW SEL2 C25 1 nF IN Q+ C26 470 pF 50 Ω µstrip C33 10 nF C34 22 pF L5 8.2 nH VCC R5 10 Ω C35 10 nF C36 22 pF C14 220 pF R4 33 kΩ PLL ENABL 35 3 MIX VCC DO 34 4 MIX GND LO OUT 33 5 LNA GND RESNTR- 32 6 LNA IN RESNTR+ 31 7 SW GND LO OUT B 30 8 LNA VCC PLLD VCC 29 9 SW GND2 C15 4.7 nF C12 Open 50 Ω µstrip R7 0Ω C11 47 pF L3 5.6 nH C13 Open J6 LO OUT PLL VCC C9 10 nF C10 22 pF L2 5.6nH R3 0Ω C5 47 pF R2 1 kΩ 50 Ω µstrip C6 Open J5 LO OUTB C7 Open PLL GND 28 PLL VCC C37 10 nF PLL DATA 27 11 MOUT I+ MOUT IIN I- GND2 DCFB I VCC2 GND3 IF OUT I VCC3 I DATA RSSI I OSC B OSC E C19 13 100 nF 14 15 16 17 18 19 20 21 22 23 24 50 Ω µstrip C39 10 pF T1 5:1 12 C38 10 nF L6 10 µH C16 470 pF C1 33 pF R7 0Ω P2-1 C31 100 pF C32 10 nF P2-3 P1 Rev C1 010904 P3 1 IF VCC 2 GND 3 GC P3-1 P3-3 P6 1 DCFBQ 2 GND 3 VREF R11 27 kΩ R10 12 kΩ 11 J4 I DATA P2 P1-3 R12 12 kΩ IF VCC J3 IF OUT P1-1 R8 12 kΩ LE I RSSI C20 220 nF C30 10 nF C45 1 µF PLL CLK R13 27 kΩ C43 68 pF I DCFB C29 100 pF R9 27 kΩ X1 9.6 MHz C18 100 nF 2908400- R2 1 kΩ PLL DATA LE 25 IF VCC C28 10 nF C4 22 pF C2 68 pF L7 10 µH C27 100 pF C3 10 nF PLL CLK 26 IN I+ J2 I MIX OUT 10 ATTN P6-1 P6-3 Q RSSI 2 GND 3 I RSSI P4-1 NC P7 1 PLL VCC 2 GND 3 PLL ON P7-1 P7-3 P5 AMP D-Sub P4 1 1 DCFBI 2 GND 3 P8 1 ATTN 2 GND 3 RX ENABL P8-1 P8-3 TRANSCEIVERS ATTN 1 BW SEL1 2 GND 3 BW SEL2 NC 1 P5-2 2 LE P5-3 3 PLL DATA NC 4 NC 5 NC 6 NC 7 P5-8 8 PLL CLK 9 GND 11-97 RF2908 Evaluation Board Layout Board Size 3.050” x 3.050” Board Thickness 0.032”, Board Material FR-4, Multi-Layer Assembly TRANSCEIVERS 11 11-98 Rev C1 010904 RF2908 Top Mid 1 TRANSCEIVERS 11 Rev C1 010904 11-99 RF2908 Mid 2 Back TRANSCEIVERS 11 11-100 Rev C1 010904 RF2908 RF2908 IF Bandwidth Response 65.0 55.0 45.0 Gain (dB) 35.0 25.0 15.0 BW_SEL (0-0) BW_SEL (0-1) 5.0 BW_SEL (1-0) BW_SEL (1-1) -5.0 -15.0 -25.0 -35.0 0.1 1.0 10.0 100.0 IF Frequency (MHz) TRANSCEIVERS 11 Rev C1 010904 11-101 RF2908 IIP3 versus Voltage Gain Noise Figure versus Voltage Gain (Non-Matched Input Z) 40.0 10.0 -40°C -40°C +25°C 0.0 +25°C 35.0 +100°C +100°C -10.0 30.0 Noise Figure (dB) IP3 (dB) -20.0 -30.0 -40.0 -50.0 25.0 20.0 15.0 10.0 -60.0 5.0 -70.0 -80.0 0.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 Voltage Gain (dB) 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 Voltage Gain (dB) Voltage Gain versus Gain Control Voltage 90.0 -40°C 80.0 +25°C +100°C Voltage Gain (dB) 70.0 TRANSCEIVERS 11 60.0 50.0 40.0 30.0 20.0 10.0 0.0 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 Gain Control Voltage (V) 11-102 Rev C1 010904