An Active Transmitter Leakage Suppression Technique for CMOS SAW-Less CDMA Receivers

A CDMA-2000 receiver without interstage RF SAW filter is presented. An active bandpass sink filter is proposed to selectively filter the transmitted leakage after the downconversion mixer. The impact on receiver noise and linearity performances is discussed. This technique improves the triple-beat (TB) and IIP2 of the receivers by 6.5 dB each, at the expense of a small increase in DC current and noise. Designed in 0.18 μm CMOS technology, the receiver achieves 45 dB gain with uncalibrated IIP 2 of +46 dBm and triple-beat of 69 dB.