Towards non-uniformly controlled charge domain sample and hold for SDR receiver baseband stage

Abstract

The time-quantized pseudorandom sampling (TQ-PRS) offers alias attenuation. The TQ-PRS-based baseband stage in a software defined radio (SDR) profit from this advantage to relax constraints on the analog-to-digital converter (ADC) and the anti-aliasing filter (AAF). However, the spectrum analysis of the TQ-PRS-controlled ADC experimental test results shows spurious replicas which are not present in simulation results. In this paper, the presented investigations show that a charge domain sample and hold circuit prior to the ADC can attenuate the spurious replicas with at least 7 dB. A solution to more attenuate the spurious replicas consists on a discrete-time switched-capacitor filter stage in charge domain.