19-0392; Rev 1; 5/96 NUAL KIT MA ATION U EET L H A S V A E T WS DA FOLLO 800MHz to 1000MHz Transmitter ________________________Applications Direct-Sequence Spread-Spectrum Transmitter Frequency-Hopping Spread-Spectrum Transmitter FSK, GMSK, BPSK, and ASK Digital Transmitter AM and FM Analog Transmitter ________________Functional Diagram VGC MODULATION BUFFER MOD LO- MIXER OUT VGC LO INPUT BUFFER LO+ POWER AMPLIFIER MASTER BIAS ____________________________Features ♦ Low-Cost, Flexible Transmitter ♦ More than 100mW of Output Power into 50Ω ♦ Operates from 800MHz to 1000MHz ♦ Single +5V Supply ♦ 20-Pin SSOP Package ♦ Uses Less than 2µA in Power-Down ♦ More than 35dB of Power Adjustment Range ♦ LO Input Power Range from -6dBm to +6dBm ♦ 2V Linear Range on Modulation Input ______________Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX2402EAP* -40°C to +85°C 20 SSOP * An alternate marking, MAX2402CAP, has been identically tested. __________________Pin Configuration TOP VIEW VGC 1 20 GND MOD 2 19 VCC GND 3 18 GND VCC 4 17 GND GND 5 LO+ 6 15 GND LO- 7 14 OUT GND 8 13 GND SHDN 9 12 VCC MAX2402 BADJ 10 16 OUT 11 LGND SHDN BADJ SSOP ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 MAX2402 _______________General Description The MAX2402 transmitter integrates a double-balanced mixer, buffered local oscillator (LO) port, variable gain stage, and power amplifier into a single IC. It is intended for use in the 800MHz to 1000MHz band, and is compatible with both direct-sequence and frequencyhopping spread-spectrum designs in the 902MHz to 928MHz ISM band. In a typical application, a digital baseband signal is mixed with a local oscillator signal to yield a BPSKmodulated carrier at the antenna. Alternatively, the baseband input may be grounded and an FSKmodulated LO signal applied directly to the LO port. The LO port consists of a limiting amplifier that can accept a single-ended or differential signal with input power between -6dBm and +6dBm in the 800MHz to 1000MHz frequency range. The baseband modulation input is linear over a 2V range, and limits with larger signal levels within the supply range. The doublebalanced mixer has been optimized for high carrier rejection. The variable gain stage offers typically 40dB of adjustment range. The power amplifier provides more than 20dBm output power and has a bias adjustment, which allows adjustment of efficiency and harmonic distortion. A shutdown function reduces the current draw to less than 2µA in less than 10µs. The MAX2402 comes in a 20-pin SSOP package to minimize board area. MAX2402 800MHz to 1000MHz Transmitter ABSOLUTE MAXIMUM RATINGS Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C VCC ........................................................................-0.3V to +6.5V Continuous Power Dissipation (TA = +70°C) SSOP (derate 16.7mW/°C above +70°C) ......................1.33W Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS (VCC = 4.75V to 5.5V, BADJ = open, SHDN = VCC - 0.5V, VGC = VCC, MOD = open, TA = -40°C to +85°C, unless otherwise noted.) PARAMETER Supply Current Shutdown Supply Current SYMBOL ICC ICCPD Supply Voltage Range VCC VGC Input Bias Current IVGC MOD Bias Current IMOD SHDN Bias Current IPD SHDN Low Threshold VSHDN Low SHDN High Threshold VSHDN High CONDITIONS MIN TYP Not transmitting 105 SHDN = 0.5V 0.15 4.75 VGC = VCC MOD = VCC MAX mA 2 V 115 µA -320 SHDN = VCC µA 5.50 325 MOD = 0V UNITS µA 10.5 µA 0.5 V VCC - 0.5 V AC ELECTRICAL CHARACTERISTICS (MAX2402 evaluation kit, VCC = 5.0V, BADJ = 2V, SHDN = VCC, MOD = 0V, VGC = VCC, RLOAD = 35Ω, fLO = 900MHz, LO power = -3dBm, TA = -40°C to +85°C, unless otherwise noted.) SYMBOL CONDITIONS Supply Current PARAMETER ICCAC POUT = 20dBm (including current to load) 165 mA Maximum Output Power PMAX (Note 1) 21 dBm Minimum Output Power PMIN VGC = 0V (Note 1) -19 dBm Power Gain from LO PGAIN 24 dB LO Input Power Range LO Frequency Range PLO For max power out (50Ω input term) (Note 2) MIN TYP MAX UNITS -6 6 dBm 800 1000 MHz 25 MHz fLO (Note 2) MODBW (Note 2) VGC Control Range VGC (Note 2) Carrier Suppression CS MOD = 5Vp-p @ 100kHz 30 dBC 2nd Harmonic Suppression HS2 (Note 1) 22 dBC 3rd Harmonic Suppression HS3 (Note 1) 25 dBC Output IP3 (BADJ = 1.0V) IP3 fLO = 900MHz + 901MHz 28.4 dBm MOD Usable Bandwidth 1.0 2.5 Note 1: See Typical Operating Characteristics graphs. Note 2: Guaranteed by design. 2 _______________________________________________________________________________________ V 800MHz to 1000MHz Transmitter OUTPUT POWER vs. FREQUENCY vs. TEMPERATURE 10 5 0 -5 -10 22.0 MAX2402 TOC 2 +24°C 23 OUTPUT POWER (dBm) 15 -40°C OUTPUT POWER (dBm) 20 +85°C 21 19 17 -15 21.5 21.0 20.5 -20 900MHz INPUT 15 800 820 840 860 880 900 920 940 960 980 2.5 2.0 1.5 OUTPUT POWER vs. BIAS CONTROL VOLTAGE vs. FREQUENCY 800MHz 23 900MHz 21 19 17 990MHz 15 13 11 10 -10 30 50 70 90 TEMPERATURE (°C) 260 240 SUPPLY CURRENT (mA) OUTPUT POWER (dBm) -30 SUPPLY CURRENT vs. BIAS CONTROL VOLTAGE vs. FREQUENCY MAX2402 TOC 4 25 800MHz 220 200 900MHz 180 990MHz 160 140 120 9 7 100 0 1 2 3 4 5 0 1 2 4 3 5 BADJ VOLTAGE (V) BADJ VOLTAGE (V) AMPLITUDE OF 3rd & 5th HARMONICS OF MODULATED WAVEFORM OUTPUT POWER LEVEL OF 2nd AND 3rd HARMONICS OF LO TA = -40°C 10 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 MODULATION VOLTAGE, PEAK-TO-PEAK (V) (LO = 900MHz, -3dBm, MOD = 5V) OUTPUT POWER BELOW FUNDAMENTAL (dBC) MAX2402 TOC 7 (100kHz SINEWAVE MODULATION OF 900MHz LO) 42 TA = +85°C 38 TA = +24°C 34 900.5MHz 30 TA = -40°C 26 TA = +85°C 22 900.3MHz 18 TA = +24°C 14 -50 FREQUENCY (MHz) VGC (V) 39 37 35 33 31 29 27 25 23 21 19 17 15 13 MAX2402 TOC 6 1.0 20.0 MAX2402 TOC 5 -25 OUTPUT POWER (dBC) BELOW 900.1MHz OUTPUT POWER (dBm) 25 MAX2402 TOC 1 25 OUTPUT POWER vs. TEMPERATURE MAX2402 TOC 3 OUTPUT POWER vs. GAIN CONTROL VOLTAGE 3rd HARMONIC T = -40°C A TA = +24°C TA = +85°C TA = +85°C 2nd HARMONIC TA = +24°C TA = -40°C 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 BADJ VOLTAGE (V) _______________________________________________________________________________________ 3 MAX2402 __________________________________________Typical Operating Characteristics (MAX2402 evaluation kit, VCC = 5.0V, BADJ = 2V, SHDN = VCC, MOD = 0V, VGC = VCC, RLOAD = 35Ω, fLO = 900MHz, LO power = -3dBm) MAX2402 800MHz to 1000MHz Transmitter _____________________Pin Description PIN NAME FUNCTION 1 VGC Variable Gain Control Input. Connect to VCC for maximum gain. 2 MOD Baseband Modulation Input to mixer 3, 5, 8, 13, 15, 17, 18, 20 GND Ground 4, 12, 19 VCC Supply Voltage, set between 4.75V and 5.5V 6 LO+ Local-Oscillator Positive Input 7 LO- Local-Oscillator Negative Input 9 SHDN Shutdown Control Input. Low level = off, high level = on. 10 BADJ Bias Adjustment Control for power amplifier. Connect resistor from BADJ to V+ or GND (see Table 1). 11 LGND Connect 27nH inductor from LGND to GND to maximize output power. 14, 16 OUT Power-Amplifier Output _______________Detailed Description The MAX2402 transmitter is a versatile design that integrates several RF functions on a single IC. It has a wide variety of applications in portable and stationary wireless designs. Each of the functional blocks (shown in the Functional Diagram) is described in detail in the following sections. LO Inputs The LO inputs are internally capacitively coupled and self biasing. The LO port can be driven differentially or single ended. When terminated at the LO inputs with 50Ω, the transmitter will provide full output power for LO inputs from -6dBm to +6dBm with single-ended drive, and -12dBm to +6dBm with differential drive. Input power beyond this range may saturate the LO input buffer, while input power below this range may result in less output power. The limiter is two cascaded differential stages, which also isolates the LO input from the mixer. This will help reduce any frequency-pulling effects in an external LO due to mixer loading. The limiter output drives one port of a double-balanced Gilbert mixer. 4 MOD Input The mixer’s other port, the MOD input, remains linear over a 2V range from about 1.5V to 3.5V at the input. When driven with digital modulation (0V to 5V), this port will completely limit, resulting in a hard BPSKmodulated signal. Since this input is self biasing, carrier suppression can be improved by externally capacitively coupling the signal into the port (the MOD input resistance is approximately 10kΩ). This would compensate for voltage offset or duty-cycle offset at this port, thus increasing carrier suppression. This MOD self bias is designed for very low on-chip offset, resulting in excellent carrier suppression. Since this port self biases when the signal is removed from MOD, the mixer will attenuate the output power by about 40dB, resulting in further attenuation past that attained from VGC control—a useful feature for ASK modulation. VGC Stage The mixer output drives the VGC stage. This stage attenuates through a multiplication technique that does not distort the signal with increased attenuation. VGC control is nonattenuating when connected to the V CC supply. VGC will attenuate for voltages from 2.5V to 1.0V. Most attenuation occurs between 1V and 2V. Maximum attenuation is achieved below 0.8V. Typical maximum attenuation is 40dB. At or beyond 40dB of attenuation, the signal may be slightly nonmonotonic. This means that there may be a slight upturn in the signal level at the low end of the VGC control range (typically about 1dB). Because of the stability implications, we suggest that the user not plan on attenuating past 35dB within a feedback loop. Power Amplifier The VGC stage passes the signal to the power amplifier. This class AB stage will produce at least 20dBm of output power for almost the complete transmit frequency range (with T A = +25°C). See Typical Operating Characteristics. BADJ Input The BADJ input adjusts the bias of the output stage. Increasing this voltage decreases bias current in the output devices, which increases efficiency, but also increases harmonic distortion (since the stage will be pushed further toward class B operation). Decreasing BADJ’s voltage increases bias current in the output devices, resulting in higher output power and less harmonic distortion. Be sure to optimize BADJ for your application. _______________________________________________________________________________________ 800MHz to 1000MHz Transmitter Table 1. Bias-Adjust Voltage for Various Resistor Values Resistor Value (Ω) BADJ with Resistor Connected to GND (V)* BADJ with Resistor Connected to VCC (V) Power Amplifier Output The power amplifier has an open-collector output that can drive into a load of 30Ω to 50Ω; however, maximum power transfer is obtained at about 35Ω. 27nH to ground is recommended on LGND (pin 11), as shown in the Typical Application Circuit. This inductor is used as a current source on the base of the output stage to pull stored charge out of the base. SHDN Input The SHDN input completely shuts down the current from the supply and all signal pins when switched below 0.5V. During normal operation, SHDN should remain above VCC - 0.5V. The shutdown control shuts down the total current to below 150nA (typ). Power-up occurs within 10µs. __________Applications Information The MAX2402 transmitter operates within the 800MHz to 1000MHz frequency range. Figure 1 shows a typical application circuit. Additional applications information can be obtained from the MAX2402 evaluation kit manual. VARIABLE GAIN CONTROL MODULATION 0.36 4.54 20k 0.63 4.27 30k 0.84 4.05 40k 1.00 3.89 39pF 1.13 3.75 100k 1.54 3.34 200k 1.89 3.00 300k 2.05 2.85 400k 2.13 2.75 500k 2.20 2.68 1M 2.31 2.57 * Typical variation of BADJ over temperature and process is less than 5%. 2 4 5 GND VCC 19 MOD VCC GND GND VCC GND GND MAX2402 18 39pF 0.01µF 17 16 OUT 50Ω 6 VCO 50k 20 VGC 3 VCC 10k 1 7 LO+ GND LO- OUT GND GND 15 VCC 47nH 14 50Ω 8 SHUTDOWN CONTROL 9 SHDN VCC BADJ LGND 10 300k 13 12 39pF VCC 11 27nH Figure 1. Typical Application Circuit _______________________________________________________________________________________ 5 MAX2402 BADJ can be left open or adjusted with a single pullup or pull-down resistor to VCC or GND, respectively. The value of this resistor determines the amount of adjustment applied. A single resistor results in no current flow at BADJ during power-down (whereas a resistor divider always has current flowing through the resistors). Table 1 shows the approximate bias adjust voltage at the pin for different resistor values. At lower LO frequencies, where the transmitter gain and output power is the highest, setting BADJ to a low voltage (maximum bias current) causes excessive current in the output and can cause unstable behavior in the IC. At lower LO frequencies (around 800MHz), more than 22dBm of power is easily obtained with BADJ set for 3V or more. If higher bias current and less distortion is desired in the 800MHz range, using a lower inductor value on LGND (pin 11) (see the Typical Application Circuit) might make the desired bias level stable. At higher frequencies (near 1000MHz), a lower bias level voltage results in more power (see the Output Power vs. Bias Control Voltage vs. Frequency graph in the Typical Operating Characteristics). MAX2402 800MHz to 1000MHz Transmitter ________________________________________________________Package Information DIM A A1 B C D E e H L α e E H INCHES MAX MIN 0.078 0.068 0.008 0.002 0.015 0.010 0.009 0.005 0.289 0.278 0.212 0.205 0.0256 BSC 0.311 0.301 0.037 0.022 8˚ 0˚ MILLIMETERS MIN MAX 1.73 1.99 0.05 0.21 0.25 0.38 0.13 0.22 7.07 7.33 5.20 5.38 0.65 BSC 7.65 7.90 0.55 0.95 0˚ 8˚ 21-0003A D α A 0.127mm 0.004in. B 6 A1 C L 20-PIN SSOP SHRINK SMALL OUTLINE PACKAGE _______________________________________________________________________________________