Evaluates: MAX2678 MAX2678 Evaluation Kit General Description Benefits and Features The MAX2678 evaluation kit (EV kit) is an easy-to-use Flexible Evaluation of the MAX2678 IC platform that enables straightforward evaluation of the Stand-Alone AMP 1 or AMP 2 Configuration MAX2678 two-stage high-performance GPS LNA, which Cascade Configuration with Interstage SAW Filter* is designed for use in demanding automotive applica- Optimal Matching and Coupling Eliminates Tuning tions and provides 35dB gain. The EV kit includes all All Ports Matched to 50 and Accessible through functionality that would typically be found in a typical SMA Connectors for Simple Interfacing remote antenna module, with the exception of a 12V Proven PCB Layout regulator. Optimal matching and coupling circuits are included on the EV kit, enabling plug and play operation. Fully Assembled and Tested In many applications, an interstage SAW filter is used to *SAW filter not included. maximize immunity to out-of-band interferers. A pair of common SAW filter footprints are available to enable evalu - ation in this configuration. Resistor options are provided to enable stand-alone testing of either gain stage or cascade Ordering Information appears at end of data sheet. testing of the two gain stages and optional SAW filter. Interfacing the MAX2678 EV kit to RF test equipment is streamlined using industry-standard SMA connectors. MAX2678 EV Kit Board Photo 19-8719 Rev 0 11/16Evaluates: MAX2678 MAX2678 Evaluation Kit Measure IP3 of AMP 1 (AMP 2 Can be Measured in Quick Start a Similar Manner) Required Equipment This procedure details how to conduct a two-tone test for MAX2678 EV kit IP3. Note that two signal generators are required. Always be aware of the possibility of interaction between the signal Linear DC power supply capable of sourcing at least generators, although the power levels used in this case are 100mA between 3V and 5.25V modest, so this is only a moderate concern. Regardless, Network analyzer it is a good idea to use attenuators or isolators to ensure Noise figure meter sufficient isolation and to be prepared for some trouble- Two RF signal generators with maximum RF power shooting and a few iterations of testing. level of at least 0dBm 1) Disable RF generators and connect them together Spectrum analyzer through a hybrid combiner. Power meter 2) Set RF frequencies of generators to 1575MHz and 1576MHz, respectively. Procedure 3) Connect output of combiner to power meter. The EV kit is fully assembled and tested and can be tested Enable generators one at a time and adjust the output directly out of the box. The following procedures provide level such that each generator is delivering -35dBm examples of how to measure common specifications of the to the power meter (depending on the power meter, MAX2678. the level may need to be calibrated at a higher level Measure the Stand-Alone Gain of Each Gain Stage and then backed off to achieve the desired -35dBm Follow the steps below to measure the stand-alone gain value). of each of the two gain stages. Full 2-port S parameters 4) Disable signal generators, connect combiner output can be measured using this procedure, but be aware that to spectrum analyzer, and then enable generators. the observed angle will not be referenced to the devices 5) Adjust spectrum analyzer and confirm that IM3 pins. Detailed discussion of calibrating S parameter products cannot be observed at 1574MHz or 1577MHz. measurements is beyond the scope of this document. If IM tones are observed, adjust spectrum-analyzer 1) Configure the network analyzer with -35dBm RF power attenuation level to confirm whether the IM is level and 800MHz to 2000MHz frequency span. generated in the spectrum analyzer or generators. If the IM is created by the signal generators, add addi- 2) Perform 2-port calibration of the network analyzer. tional isolation and recalibrate the level as needed. 3) Disable power-supply output, adjust output level to 5V, and set current limit to at least 100mA. 6) Disable generators and then connect output of combiner to the AMP 1 input (IN1, J5). 4) Connect supply leads to connector JU1 on the EV kit. 7) Connect output of AMP 1 (OUT1, J7) to spectrum 5) Connect network analyzer to AMP 1 (Port 1 = J5, analyzer and increase spectrum-analyzer attenua- Port 2 = J7). tion by approximately 15dB (this helps to eliminate 6) Enable power supply. uncertainty whether any distortion is generated in the 7) Measure S21 of AMP 1. spectrum analyzer). 8) Disable power supply. 8) Confirm 5V power supply connection to EV kit connector JU1 and then enable the supply output. 9) Connect network analyzer to AMP 2 (Port 1 = J4, Port 2 = J6). 9) Enable signal-generator outputs. 10) Enable power supply. 10) Measure IM3 using spectrum analyzer and calculate IP3 assuming input power level of -35dBm/tone. 11) Measure S21 of AMP 2. By default, AMP 2 is in high- gain mode (component R7 open). Maxim Integrated 2 www.maximintegrated.com