Evaluates: MAX2685 19-1493 Rev 0 7/99 MAX2685 Evaluation Kit General Description Features The MAX2685 evaluation kit (EV kit) simplifies testing of +2.7V to +5.5V Single-Supply Operation the MAX2685. This EV kit allows evaluation of the low- 50 SMA Inputs and Outputs noise amplifier (LNA) as well as the downconverter mixer. Fully Assembled and Tested Allows Testing of All Device Functions Component List DESIGNATION QTY DESCRIPTION Ordering Information C1, C3, C5, 4 0.1F ceramic capacitors C17 PART TEMP. RANGE IC PACKAGE C2, C14, C15 0 Not installed MAX2685EVKIT -40C to +85C 16 QSOP C4, C8 2 47pF ceramic capacitors C6, C7, C10 2 330pF ceramic capacitors Quick Start C9 1 3.3pF ceramic capacitor The MAX2685 EV kit is fully assembled and factory C11, C18 2 6pF 0.1pF ceramic capacitors tested. Follow the instructions in the Connections and C12 1 1000pF ceramic capacitor Setup section for proper device evaluation. C13 1 12pF 0.1pF ceramic capacitor Test Equipment Required 10F tantalum capacitor This section lists the equipment recommended for veri- C16 1 AVX TAJC106K016 fying the MAX2685s operation. It is intended as a guide only some substitutions are possible. 12nH inductor L1 1 Toko LL1608-SH12NK Two RF signal generators capable of delivering at least 0dBm of output power at frequencies to 2GHz 680nH 5% inductor L2 1 (HP 8648C or equivalent). One generator is required Coilcraft 1008CS-681XJBC 5% for the local oscillator (LO) source the other is 820nH 5% inductor L3 1 required for the mixer and LNA RF input. Only one Coilcraft 1008CS-821XJBC 5% generator is required to operate the LNA. L4 1 Not installed An RF spectrum analyzer that covers the MAX2685s R1, R2 2 1k resistors operating frequency range (the HP 8561E, for exam- R3 1 75 resistor ple). R4 1 15k resistor A power supply that can provide up to 100mA at +2.7V to +5.5V. R5 1 0 resistor An ammeter for measuring the supply current R6, R7, R8 3 Not installed (optional). IFOUT+, Several 50 SMA cables. IFOUT-, LNAIN, 6 SMA connectors (PC edge mount) LNAOUT, LO, Connections and Setup MIXIN This step-by-step guide explains how to get the EV kit JU1, JU2 2 3-pin headers operational and how to evaluate both the LNA and the GND, V 2 Eyelets CC downconverter mixer. U1 1 MAX2685EEE (16-pin QSOP) None 1 MAX2685 PC board Maxim Integrated Products 1 For free samples & the latest literature: MAX2685 Evaluation Kit Low-Noise Amplifier (LNA) 4) Connect the other RF signal generator (with the out- 1) Connect the SHDN jumper (JU2) on the EV kit to the put disabled) to the MIXIN SMA connector. Set the ON position, SHDN = V . This enables the frequency to 880MHz and the amplitude to -25dBm. CC MAX2685. 5) Connect the spectrum analyzer to the IFOUT+ SMA 2) Connect the GAIN jumper (JU1) on the EV kit to the connector. Set the spectrum analyzer to an 80MHz HI position, GAIN = V . This places the LNA in center frequency, a 1MHz span, and a 0dBm refer- CC high-gain mode. ence level. 3) Connect a 3V DC supply (through an ammeter, if 6) Turn on the LO and RF signal generators. desired) to the V and GND terminals on the EV kit. CC 7) An 80MHz signal should show on the spectrum ana- 4) Connect one RF signal generator to the LNAIN SMA lyzers display and should indicate a typical gain of connector. Do not turn on the generators output. Set 6.1dB after accounting for cable losses. the generator for an output frequency of 880MHz 8) If desired, connect the GAIN jumper (JU1) on the EV and a power level of -30dBm. kit to the LO position, GAIN = GND. This places 5) Connect a spectrum analyzer to the LNAOUT SMA the mixer in low-gain mode. An 80MHz signal should connector on the EV kit. Set the spectrum analyzer appear on the spectrum analyzers display and to a center frequency of 880MHz, a total span of should indicate a typical gain of 4.6dB after 200MHz, and a reference level of 0dBm. accounting for cable losses. 6) Turn on the DC supply. The supply current should Detailed Description read approximately 8.5mA (if using an ammeter). The MAX2685 EV kits circuitry is described in this sec- 7) Activate the RF generators output. An 880MHz sig- tion. For more detailed information about the operation of nal should show on the spectrum analyzers display the device itself, refer to the MAX2685 data sheet. and should indicate a typical gain of 15dB after accounting for cable losses. Low-Noise Amplifier The LNA circuitry consists of matching networks and 8) Test the MAX2685s low gain mode by changing the DC-blocking capacitors at the input and output. output power on the signal generator to -10dBm and setting the GAIN jumper (JU1) on the EV kit to the Downconverter Mixer RF Input LO position, GAIN = GND. The supply current The downconverter mixers RF input, MIXIN, requires a should read approximately 4mA (if using an amme- simple matching network. C10 provides DC blocking, ter). An 880MHz signal should show on the spectrum and C9 is used to match the input to 50 at 880MHz. analyzers display and should indicate an attenuation of 12dB after accounting for cable losses. Downconverter Mixer LO Input The downconverter mixers LO input is terminated with 9) If desired, test the shutdown feature by moving the a 75 resistor, R3, at the SMA input. C8 provides DC SHDN jumper (JU1) into the OFF position. This dis- blocking. ables the part and reduces supply current below 1.0A. Downconverter Mixer Differential IF Output Downconverter Mixer The mixer output can be evaluated in either a single- 1) Connect the GAIN jumper (JU1) on the EV kit to the ended or differential configuration. The MAX2685 EV kit HI position, GAIN = V . This places the mixer in CC is shipped with a differential to single-ended converter high-gain mode. for single-ended testing. See the IF Output Configuration 2) Remove the RF signal generator and spectrum ana- section. lyzer from the LNAIN and LNAOUT connections. The DC supply connections needed for testing the mixer are the same as in the LNA section. 3) Connect one RF signal generator (with the output disabled) to the LO SMA connector. Set the frequen- cy to 960MHz and the output power to -8dBm. 2 Evaluates: MAX2685