Frequency-downconversion and IF channel selection A-DQS sample-and-hold pair for two-step-channel-select low-IF receiver

A novel I/Q sample-and-hold (S/H) pair for a recently proposed two-step-channel-select low-IF receiver, which performs both IF-to-baseband frequency down-conversion and IF channel selection, will be presented. Both functions are mainly implemented through a controllable Analog-Double Quadrature Sampling (A-DQS) technique, which can effectively perform forward/backward frequency shifting through simple digital control. Thus, a new two-step channel selection method is proposed to significantly relax the front-end frequency synthesizer phase noise and locking time requirements, by partitioning the channel selection process from the FS to the proposed S/H pair. A prototype is designed in CADENCE™ environment with 0.35-μm CMOS process parameters and adopting various circuit techniques for minimization of the image problem due to the I/Q mismatch.