REP016: Japanese 110MHz IF dual-band cellular CDMA RF front-end

Rapid engineering prototypes are actual circuits that Maxim application engineers build in the lab and conduct product testing. They are the starting point for new RF engineering designs. They are not intended to be used as assessment testing tools.

Purpose: To convert the radio frequency (RF) matching circuit from the US cellular band to the Japanese cellular band to test the performance of the CDMA dual-mode RF front-end IC.

The MAX2325 application circuit was modified from a standard BOM suitable for US cellular LNA and mixer RF matching to a standard circuit compliant with Japan's 110MHz IF. In addition, we also designed a test circuit to meet the needs of end users. Experiments have proven that the performance of MAX2325 is completely consistent with the test data listed in the data sheet under the US cellular band.

The MAX2325 evaluation board is used to evaluate the performance of the MAX2325 as an extension of the MAX2325 functionality.

The MAX2325 low-noise amplifier and mixer is specially designed for single-band CDMA cellular phones, but it can also be used in TDMA, GSM or EDGE systems in the 800MHz to 900MHz frequency band. Unlike the previous product MAX2324, it adds a third internal amplifier to the LNA. Three-stage "mid-gain" amplifier with increased conversion hysteresis margin. The MAX2325 comes in an ultra-small package (28-QFN) and has a high third-order input intercept point.

Block diagram of a receive-path application
Bill of materials, part 1
Bill of materials, part 2
Schematic of the MAX2323 evaluation kit with the MAX2325 IC installed (PDF, 58kB)