Abstract: Reference design (RD) is a dual-band, triple-mode CDMA front-end IC in a receiver with all 183MHz IFs for processing cellular CDMA. The RD uses the MAX2323, a low-noise amplifier (LNA) with mixer, that is useful for TDMA, GSM, EDGE, and WCDMA applications.
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Objective: To apply and measure this dual-band triple-mode CDMA front-end IC in a receiver with all 183MHz IFs.
The MAX2323 was developed with a single, digital, IF output port. Having a common 183MHz IF, both digital mixers' gain is still adequate for good receiver sensitivity, and their IP2 performance and other related parameters offer sufficient margin for meeting 1/2 IF and additional interferers in a CDMA handset. In this application, the MAX2323 was tested for and successfully applied to a CDMA dual-band dual-mode handset front-end design. The circuit modification requirement for this project was to retune the FM analog and the cellular/PCS digital mixers to 183MHz IF.
The MAX2323 low-noise amplifier (LNA) plus mixer is designed for dual-band CDMA cellular-phone handsets, but it can also be used in dual-band TDMA, GSM, EDGE, or WCDMA applications. It differs from its predecessor (the MAX2320) by adding a third "mid-gain" state for the cellular-band LNA that improves switchover hysteresis margin. It also comes in a smaller package (28-QFN) and offers increased third-order input intercept.
Tested Circuit 
