a 900 MHz RF Transceiver AD6190 The receiver section includes a Low Noise Amplifier (LNA). The LNA’s output drives an image-reject mixer; the mixer’s output optimized for 10.7 MHz is filtered and processed by the limiting IF amplifier. FEATURES Complete 900 MHz RF Transceiver LNA Receive Mixer Transmit Mixer Driver Amplifier VCO Prescaler Limiter Amplifier with RSSI On-Chip Low Dropout Regulator Independent Sleep Modes for TX, RX 28-Lead SSOP Package The transmit section accepts a modulated 10.7 MHz IF input, and uses an image-reject upconverter to mix the signal up to the 902 MHz–928 MHz RF carrier frequency while suppressing the unwanted image and LO components. The RF output is raised to a nominal 0.5 milliwatt (–3 dBm) output level. This output can be used directly or can drive an external power amplifier to higher levels. The on-chip VCO operates at 2× the local oscillator frequency. This reduces oscillator pulling due to strong interferers in-band or transmitter leakage. An on-chip 64/65 prescaler allows the VCO to be controlled by a low cost 15 MHz CMOS synthesizer. APPLICATIONS 902 MHz–928 MHz ISM Band Cordless Telephones 902 MHz–928 MHz ISM Band Wireless Data Systems An on-chip low dropout regulator minimizes VCO pushing. The transmit section, receive section, or both, can be placed in a low current SLEEP mode when not in use. The AD6190 900 MHz RF transceiver is packaged in a 28-lead SSOP package. GENERAL DESCRIPTION The AD6190 900 MHz RF Transceiver provides a complete RF/IF section for systems operating in the 902 MHz–928 MHz license-free ISM band. The high level of integration allows several dozen discrete components to be replaced. It is ideally suited for use in cordless telephone and wireless data applications. The AD6190 900 MHz RF Transceiver is part of the Analog Devices/Zilog “A-to-Z Phone” Spread-Spectrum System for cordless telephone and data communications applications. Contact Zilog directly at (408) 370-8000 for more information on the Z87000 series baseband controller chips. FUNCTIONAL BLOCK DIAGRAM 10.7 10.7 RSSI 0 90 ANT FILTER LIMOUT VREG AD6190 T/R S/W TXON VCO POWER MANAGEMENT AND CONTROL /2 PA I Q RXON VCOON Z87L00 SPREADSPECTRUM CONTROLLER VBATT 64/65 VOLTAGE REGULATOR VREG 0 90 10.7 15MHz SYNTHESIZER REV. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 1998 (@ TA = +258C, VCC = +3.3 V, FIF = 10.7 MHz, FRF = 902 MHz–928 MHz, TX IF Input AD6190–SPECIFICATIONS level 137 mV p-p, unless otherwise noted) Parameter RECEIVE RF SECTION (LNA to Mixer Output) Power Gain Noise Figure 1 dB Compression (Input) Input IP3 Image Rejection TRANSMIT UPCONVERTER Image Rejection LO Feedthrough Conditions Min Typ FRF = 915 MHz, FLO = 904.3 MHz 28 24 4.2 –30 –17 33 dB dB dBm dBm dBc FIF = 10.7 MHz, FLO = 904.3 MHz FIF = 10.7 MHz, FLO = 904.3 MHz 35 48 –33 dBc dBm –3 +4.5 dBm dBm For IF Input Level = 137 mV p-p VCO Operating Frequency (LO Frequency ×2) IF LIMITER AMPLIFIER First Stage Gain Second Stage Gain AC Output Level DC Level IF Port Impedance RSSI OUTPUT Slope Output Voltage Linear Range RSSI Log Conformance Error Units Source Z = 50 Ω, IF Load Z = 330 Ω DRIVER AMPLIFIER Nominal Output Power 1 dB Compression PRESCALER Division Ratio PREMOD = “1” PREMOD = “0” Output Level Max 0 1783 RL = 2.2 k, CL < 10 pF 0.55 RL > 30 kΩ, CL < 30 pF FIF = 10.7 MHz With 10 Ω in Series with VCCIF @ –100 dBm RF Input @ –30 dBm RF Input (With Respect to RF Input Level) SUPPLY CURRENT Transmit Mode Receive Mode Sleep Mode (VCC = 3.3 V) TXON, VCOON = 1; RXON = 0 RXON, VCOON = 1; TXON = 0 TXON, VCOON, RXON = 0 SUPPLY VOLTAGE Other Supplies VBATT VCCTX, VCCIF, VCCLNA 3.0 3.0 VCO REGULATOR Output Voltage, 3.0 < VBATT < 4.6 V TEMPERATURE RANGE 1835 MHz 64 65 1.0 V p-p 24 70 450 1.76 330 dB dB mV p-p V Ω 22 0.90 2.40 70 ±2 mV/dB V V dB dB 93 59 270 mA mA µA 4.6 3.6 V V 2.65 2.85 V –20 +85 °C 3.3 Specifications subject to change without notice. –2– REV. 0 AD6190 ABSOLUTE MAXIMUM RATINGS 1 NOTES 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. 2 Thermal Characteristics: 28-lead SSOP package θJA = 122°C/W. 1 Supply Voltage VBATT, VCCIF, LNAVCC, VCCTX to GND . . . . +5.5 V Maximum RF Input Level Without Damage . . . . . . . +20 dBm Internal Power Dissipation2 . . . . . . . . . . . . . . . . . . . . 500 mW Operating Temperature Range . . . . . . . . . . . –25°C to +85°C Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C Lead Temperature Range (Soldering, 60 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . +300°C ORDERING GUIDE Model Package Description Package Option AD6190ARS AD6190ARSRL 28-Lead Shrink Small Outline 28-Lead Shrink Small Outline, Supplied on Reels, 1500 Units per Reel RS-28 Minimum order quantity 25,000 units. CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD6190 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. WARNING! ESD SENSITIVE DEVICE MODULUS CONTROL 82pF TXON VCOON VBATT (3.0-4.5VDC) AD6190 1nF PRESCALER OUT 1.96kV 64/65 1 R3 51.1V 82pF 82pF 2 82pF 82pF 3 0.1mF 220V Q1 39V 15nH VCCTX (3.3VDC) 10nF 82pF REG 10nF VCC DRIVER (3.3VDC) 8.2nH TRANSMIT RF OUT 4 2.2pF L1 5 TUNE VOLTAGE IN C1 15nH 10V IN 6 82pF 39V 42 LIMITER OUT D1 L2 15nH 7 0.1mF 82pF 8 RSSI OUT 220V 10nF 82pF RXON 2.2pF 82pF VCCLNA (3.3VDC) 15nH LNA IN 10 TRANSMIT IF IN 100nF 9 2.75 VDC 0.1mF 82pF 82pF 11 82pF 54.9V 301V 12 F1 6.8pF RSSI 1kV 6.8mH (TDK2012) 82pF 10V VCC MIXER 100nF 39V (3.3VDC) 13 14 27pF F1 U1 82pF 10nF 100nF Figure 1. Test Circuit REV. 0 –3– 82pF 10V VCCIF (3.3VDC) AD6190 PIN FUNCTION DESCRIPTIONS No. Pin Name Type Function/Description 1 PREOUT Output 2 3 4 5 6 7 8 9 10 11 12 13 14 VCOON VBATT VBASE TANK– GND TANK+ RSSI TXIF VREG RXON LIMIN IFAMPCOM IFAMPOUT Control Power Power Input Power Input Output Input Power Control Input Input Output 15 16 17 IFAMPIN VCCIF RXMIXOUT Input Power Output 18 19 20 21 22 23 24 25 26 27 28 LNAGND GND RFIN VCCLNA GND LIMOUT PAGND RFOUT VCCTX TXON PREMOD Power Power Input Power Power Output Power Output Power Control Input Prescaler Output. Usually connected to input of external low frequency CMOS synthesizer (Fujitsu MB87006A, Siemens PMB2307, or similar). Logic “1” turns on power to VCO, and divider/prescalers. VBATT connection for regulator. Normally connected to 3.3 V dc or battery. Base connection to external regulator pass transistor (MMBT3906 or similar). Connection for VCO tank circuit (LC network). Substrate ground connection. Connection for VCO tank circuit (LC network). Received Signal Strength Indicator output signal. Accepts modulated transmit signal at 10.7 MHz IF. Regulated VCC for LO from external pass transistor. Logic “1” turns on power to LNA and receive mixer stages. Input to limiting amplifier. Input signal common for limiting amplifier. Output of first stage of IF amplifier. Normally connected through 10.7 MHz filter to Pin 12 (LIMIN). Input to first stage of IF amplifier. Local VCC connection for IF amp/limiter stages. 10.7 MHz IF Output. Normally connected through 10.7 MHz filter to IF amplifier input (Pin 15). Local ground for LNA. Substrate ground connection. LNA Input. Normally driven single-ended from 50 Ω source impedance. VCC for LNA. Substrate ground connection. 10.7 MHz limiter output. Local ground for PA stage emitter. Degeneration may be added. Transmitted RF output signal at 0 dBm level. Local VCC connection for TX stages. Logic “1” turns on power to transmit mixer, buffers, and PA stages. Prescaler Modulus control (HIGH = divide-by-64; LOW = divide-by-65). PIN CONFIGURATION PREOUT 1 28 PREMOD VCOON 2 27 TXON VBATT 3 26 VCCTX VBASE 4 25 RFOUT TANK2 5 24 PAGND GND 6 23 LIMOUT TANK+ 7 RSSI AD6190 TOP VIEW 22 GND 8 (Not to Scale) 21 VCCLNA TXIF 9 20 VREG 10 19 LNAGND RXON 11 18 LNAGND RFIN LIMIN 12 17 RXMIXOUT IFAMPCOM 13 16 VCCIF IFAMPOUT 14 15 IFAMPIN –4– REV. 0 2.5 1000 2.25 900 2.0 800 1.75 700 1.5 1.25 LIMITER – V-p-p RSSI – Volts AD6190 3.3V +258C 915MHz 3.3V –258C 915MHz 1.0 3.3V +858C 915MHz 0.75 600 500 400 300 0.5 200 0.25 100 0 –115 –105 –95 –85 –75 –65 –55 PIN – dBm –45 –35 –25 0 –25 –15 –15 Figure 2. RSSI Voltage vs. Input Power –5 5 15 25 35 45 TEMPERATURE – 8C 55 65 75 85 Figure 5. Limiter Output Level vs. Temperature @ 3.3 V and 915 MHz MKR 915.0 MHz 0.0 dBm #AT 30 dB 2.5 2.25 2.0 MARKER 915.0 MHz 0.0 dBm RSSI – Volts 1.75 3.0V +258C 915MHz 1.5 1.25 L.O. 3.3V +258C 915MHz IMAGE 1.0 3.5V +258C 915MHz 0.75 0.5 0.25 0 –115 –105 –95 –85 –75 –65 –55 PIN – dBm –45 –35 –25 –15 CENTER 915.0 MHz #RES BW 10 kHz Figure 3. RSSI Voltage vs. Input Power SPAN 150.0 MHz SWP 4.50 sec VBW 10 kHz Figure 6. Frequency Spectrum Tek Run: 4.00GS/s ET Average [ 5.0 T V: 72.0ns @: –41.5ns C1 Freq 13.899MHz C1 +Duty 60.1% 4.0 3.0 RSSI ERROR – dB ] 2.0 1.0 0 –1.0 –2.0 –3.0 –4.0 –5.0 –115 –105 –95 –85 –75 –65 –55 PIN – dBm –45 –35 –25 Ch1 10.0mV –15 Figure 7. Prescaler Output Figure 4. RSSI Error vs. Input Power REV. 0 M 12.5ns Ch1 –5– 0V AD6190 PRODUCT DESCRIPTION The AD6190 is a complete RF/IF transceiver for operation in the 902 MHz–928 MHz Industrial, Scientific and Medical (“ISM”) frequency band. Together with a suitable spreadspectrum controller, the AD6190 can be used to design a spread-spectrum system compliant with FCC “Part 15” (47CFR15.247) regulations. The AD6190 is a fully compatible companion chip to the Zilog Z87L00 “ZPhone” frequencyhopping spread-spectrum controller. LO RF IN The AD6190 includes a receive path of LNA, image-reject mixer, IF amplifier and limiter amplifier with RSSI. The transmit path accepts a 10.7 MHz IF input signal, and uses imagereject upconversion to the 902 MHz–928 MHz band. Frequency control is achieved using an on-chip VCO and dual-modulus prescaler connected to an inexpensive low frequency PLL for channel selection and frequency hopping. Additionally, an on-chip voltage regulator stabilizes the VCO to prevent LO pushing due to power supply variations. APPLYING THE AD6190 Receive Signal Path The AD6190 Low Noise Amplifier (LNA) and image-reject mixer together provide downconverter with a total gain of 24 dB and a typical Noise Figure (NF) of 4.2 dB. The LNA input port exhibits an impedance of 320-j61 at 915 MHz. In order to provide an optimum match to a 50 Ω source, the network shown in Figure 8 should be used. 908 Figure 9. Image-Reject Mixer The RF signal, containing both the desired signal at (FLO + FIF) and another possible signal at the image frequency of (FLO – FIF) is applied to two mixers in parallel. These mixers are driven by local oscillator signals in quadrature. The mixer outputs at the two mixer IF ports contain both the desired signal and the image signal. However, the outputs of the two mixers are in quadrature (shifted 90 degrees relative to each other). The outputs of the two mixers are then shifted another 90 degrees relative to each other in a phase-shift network. The two mixer outputs thus contain the desired signal and the image signal exactly 180 degrees out of phase. By adding (or subtracting) the two signals, the undesired image signals cancel, the desired signal components add, and image-rejection occurs. Local oscillator leakage is suppressed by the use of doubly-balanced mixers. The mixer output that drives the input side of the first 10.7 MHz filter should also be connected through a parallel RLC network of 6.8 pF, 1 kΩ, and 7 pF to the power supply to match the 330 Ω filter impedance. RF IN 2.2pF IF OUT The quality of the image rejection is a function of the phase and amplitude matching of the quadrature branches of the LO and IF phase-shift networks. In the AD6190, image-rejection is typically 33 dB. 82pF 50V AD6190 908 15nH The 10.7 MHz IF signal is then filtered and amplified by a 24 dB fixed gain. The output of this stage is further filtered, and applied to a 6-stage limiting amplifier. The limiter output signal is typically 450 mV p-p into a 30 kΩ, 30 pF load, with a dc offset level of approximately 1.76 V dc. AD6190 Figure 8. LNA Input Matching Circuit All 10.7 MHz IF filters are assumed to be standard 330 Ω impedance ceramic types. The AD6190 RX IF signal chain and TX IF input includes internal matching resistors for this impedance. The frequency plan of the AD6190 provides the lowest possible RF implementation cost. A single conversion design is used with a 10.7 MHz IF to take advantage of the very low cost filters available. However, since the 902 MHz–928 MHz band is wider than twice the IF, it is possible that undesired in-band signals will be mixed down to the IF. These images could cause interference to the desired signal. It is thus necessary to provide tunable filtering before the receive mixer, or some other approach to eliminate interference from image signals. When used with the Zilog Z87L00 Spread-Spectrum Controller IC, the 10.7 MHz IF signal contains the received data encoded in FSK modulation with approximately a ±33 kHz deviation. The Z87L00 performs the FSK demodulation in the digital domain. The RSSI (Received Signal Strength Indicator) signal represents the strength of the received signal, linear in dB, and scales with supply voltage. With a 3.3 V supply (through a 10 Ω resistor on the VCCIF pin), an RF signal level of –100 dBm at the LNA input will produce an RSSI voltage of approximately 900 mV. The RSSI voltage will increase with increasing RF input level, at approximately 22 mV/dB to approximately 2.4 V at –30 dBm input. The RSSI output voltage remains above 2.4 V for input levels up to +15 dBm. In the AD6190, a technique known as “image-reject” (or SSB) mixing is used. This technique suppresses image interference by using a pair of mixers with quadrature local oscillators. See Figure 9. –6– REV. 0 AD6190 other words, the Pin 5 and Pin 7 pads are simply extended to form L1 and L2. Equivalent Hi-Q chip inductors in the 2.2 nH to 4.7 nH range may be substituted. Transmit Signal Path The AD6190 transmit chain is designed to accept an input signal generated by the Z87L00 device. The Z87L00 provides a digitally-generated FSK signal at 2.508 MHz, sampled at 8.192 MSPS. This sampling process produces a signal with components at 2.508 MHz, 5.684 MHz, 10.7 MHz, 16.386 MHz, and other higher-order image products at frequencies of (N × 8.192 MHz ± 2.508) MHz. This signal is filtered to select the 10.7 MHz image, which is used as the transmit IF signal for the AD6190. The single tuning varactor, D1, (e.g., Alpha Industries SMV1233-011) and a fixed capacitor C1 (or a common anode dual diode) are located on the ends of the lines. Note that this is a positive supply (VREG) referenced “pump-down” tank, meaning that as the TUNE voltage is increased toward VREG, the frequency goes down. The loop filter return should also be referenced to VREG (not ground) in order to minimize common-mode noise pickup and frequency pushing. The designer is cautioned to develop a tank with only as much kVCO as required to allow easy coverage of the band with respect to component tolerance and production issues, in order to minimize phase noise and frequency pulling. An image-reject transmit up-converts the 10.7 MHz IF signal to the 902 MHz–928 MHz RF band, with image and spurious outputs typically 45 dB below the desired signal, and LO leakage typically –33 dBc. The on-chip driver can provide at least 1 mW (0 dBm) into a 50 Ω load. However, when driving an external Power Amplifier (PA) with a gain of 15 dB or more, we recommend a nominal driver output power no higher than –3 dBm (137 mV p-p TX IF input level) to avoid spurious PA output products in excess of FCC allowances. The RFOUT pin is normally connected through an 8.2 nH dc feed inductor, and ac-coupled to the power amplifier. 39V 15nH 15nH VTUNE (FROM LOOP FILTER) C1 L2 TANK– D1 LOOP FILTER RETURN +3.3V 39V 15nH GND L1 TANK+ 100nF AD6190 8.2nH VCLO (FROM REGULATOR PASS TRANSISTOR) 2.2pF TXOUT 82pF AD6190 TO 50V LOAD Figure 11. Typical VCO Tank Circuit An on-chip dual-modulus (64/65) prescaler allows the frequency control to be done with a low-cost low-frequency PLL synthesizer chip, such as the Fujitsu MB87006A, Siemens PMB2307, or similar. Figure 10. TXOUT Matching Circuit The prescaler output should be connected to ground through a 2.2 kΩ pull-down resistor. The output signal (typically 1 V p-p) is sufficient to drive most low cost PLLs, and is usually accoupled through a 1 nF capacitor to the PLL input. Frequency Control The AD6190 includes an on-chip voltage controlled oscillator for LO generation. An external varactor-tuned tank circuit controls the frequency. This VCO operates at twice the required LO frequency for several reasons. Layout, Grounding and Decoupling The AD6190 is a complex device with high bandwidth and high gain on-chip. Proper layout, grounding and decoupling, techniques are essential to realizing the full performance of the system. Each of the power supply pins should be decoupled to ground at the chip using a 82 pF chip capacitor in parallel with a 10 nF chip capacitor. The VCCIF pin requires a 10 Ω series resistor in addition to the 82 pF shunt capacitor. First, it is a simple matter to generate the I and Q LO components needed for the image-reject mixers by starting with a LO at twice the desired frequency. The divide-by-two process can easily provide coarse quadrature signals. Any remaining phase error is further reduced by an on-chip connection network. Second, by keeping the oscillator operating at a frequency far removed from the RF carrier frequency, parasitic feedback from either the transmit signal or strong received signals is minimized. This reduces VCO “pulling” effects. Voltage Regulator The AD6190 includes an on-chip voltage regulator to stabilize the supply voltage for the local oscillator, isolating it from any variations or noise on the main power supply voltage in the system. This regulator is nominally set for 2.75 V output. An external PNP pass transistor provides the needed output current for the VCO. A typical series resonant VCO tank circuit is shown in Figure 11. The oscillator actually operates at twice the required LO frequency band. The tank inductors (L1, L2) may be implemented as printed traces on the PC board or as lumped circuit chip components. The printed lines are implemented in nonmicrostrip to produce higher Q. At least two foil layers should be removed immediately under the tank area. A suitable tank structure can be formed from two parallel lines, each approximately 7 mm long by 0.3 mm wide, continuing out from the device pads. In REV. 0 This regulator is intended to stabilize the voltage for the LO only, and should not be used for other circuitry. VBATT may be connected to a 3.3 V dc preregulator or to the preconditioned three-cell battery system. –7– AD6190 Mode Controls OUTLINE DIMENSIONS The AD6190 is designed as a time-division-duplex (TDD) radio. This means that the transmitter and receiver operate at different times. The AD6190 includes control pins to shut down unused portions of the circuit when not needed, saving power, as shown in the table below. For any mode except “Sleep,” power must be applied to VBATT Pin 3 and to all VCC Pins (16, 21 and 26) to ensure proper operation. Dimensions shown in inches and (mm). 28-Lead Shrink Small Outline (RS-28) 15 1 14 0.212 (5.38) 0.205 (5.21) 28 0.311 (7.9) 0.301 (7.64) NOTE: Do not enable both the transmit and receive paths simultaneously. Table I. Mode RXON TXON VCOON Notes Receive Transmit “Sleep” VCO Only 1 0 0 0 0 1 0 0 1 1 0 1 0.07 (1.79) 0.066 (1.67) 0.078 (1.98) PIN 1 0.068 (1.73) Allows VCO/PLL to settle prior to transmit time slot. C3231–8–1/98 0.407 (10.34) 0.397 (10.08) 0.015 (0.38) 0.010 (0.25) SEATING 0.009 (0.229) PLANE 0.005 (0.127) 8° 0° 0.03 (0.762) 0.022 (0.558) PRINTED IN U.S.A. 0.008 (0.203) 0.0256 (0.65) 0.002 (0.050) BSC –8– REV. 0