Abstract: This reference design (RD) shows how a dual-band, dual-mode CDMA front-end IC can drive an IRF3100 IF demodulator. The RD features the MAX2323 CDMA low-noise amplifier which is also useful for TDMA, GSM, EDGE, and WCDMA applications. Schematics, the bill of materials (BOM), and performance results are shown.
Rapid Engineering Prototypes are real circuits that Maxim application engineers have built and measured in our labs. They can provide a starting point for new RF designs. They are not available as evaluation kits.
Objective: To develop a suitable IF match between this dual-band triple-mode front-end IC and the IFR3100 IF demodulator IC, and to measure the front-end performance.
The MAX2323 offers very attractive Icc versus noise figure and linearity, so this front-end IC is found in applications replacing poorer-performing ICs from other non-Maxim chipsets. This application was developed to match the IF port to the MSM-based IFT3100 IF demodulator. Note that the MAX2323 PCSLNA was measured at a 1.9dB noise figure, which could likely be improved further given the time.
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 
