CDS noise reduction of partially reset charge-detection nodes

The paper describes noise reduction obtained by using the correlated double sampling (CDS) technique to process signals from destructively reset charge detection nodes where the resetting process has not been fully completed. In standard cases, the charge-detection-node-reset time constant is very short, which allows the node Fermi level to fully equilibrate with the reference. This article focuses on cases where the clocking frequency is high and the charge-detection-node-reset time constant is comparable or larger than the reset time interval. The derived formulas for the noise power spectral density and variance are thus more general and apply to a wider range of applications. Despite the generality, the obtained results have a closed analytic form and are useful for simple circuit and device parameter optimization programs. The results and derivations are based on a simple model and first principles to avoid tacit assumptions that are sometimes present in other previously published results.