Correlated-double sampling time-multiplexing integrator

A time-multiplexed switched-capacitor CDS equalizer with reduced crosstalk layout

“…1. The effect of can be reduced by turning on a clamp switch [1], [4], [9] during the inactive channel periods . This effectively prevents it from sharing any channel charges to the next active channel integrating capacitor.…”

“…Hence, the clamping switch method is preferred because it supports either singleended or fully differential TM-SC structures. In general, using the channel reset switch, it can be observed that the typical coupling crosstalk, from adjacent channels to far apart passbands channels, ranges from dB to dB [1], [4], [9] based on the measured results of different circuit architectures. To further improve the crosstalk range, the remaining crosstalk problem arising from needs to be resolved.…”

“…Another well-known method to reduce the op-amp offset and the switch charge injection is based on fully differential SC implementation incorporating high pass function [8]. Alternatively, further effective method to reduce the offsets is through CDS technique [4], [9] combined with minimum switch size whenever meeting the worst case speed in specification. As a matter of fact, not only does the CDS structure benefit the reduction of the noise, it is also a natural extension for the TM-SC circuits with reset feature.…”

“…Multiplexed SC filters or equalizers are popular application examples. Although TM-SC techniques [1], [4], [9] or architectures [1]- [9] have been reported successfully in relaxing certain shortcomings from the independent channel design approach, there still exist many challenging problems such as crosstalk interference signal, gain loss, dc offset, and coupling noise that limit the circuit performance. Among these imperfect factors, the inter-channel crosstalk most often outweighs the achievable signal-to-noise (S/N) ratio and causes the accuracy issue in terms of gain loss in the TM integrated systems.…”

“…In addition, dependent upon the applications, the potential large dc offset or mismatched dc components among different channels may cause a harmful effect in the multi-channel system. Therefore, the objective of this paper is to study the key limitations and to present the design of a correlated double-sampling (CDS)-SC equalizer using the previously reported CDS-TM-SC integrator [9] that addresses the issues from circuit design perspective and layout perspective in order to reduce three types of crosstalk effects as well as both circuit dc offset and noise simultaneously. The experimental results are given to validate the proposed method.…”