In this paper we present a theoretical study of the errors due to imperfect reconstruction and to quantization in hybrid filter bank (HFB) analog/digital (A/D) converters, that are non uniform i.e., with K channels and an arbitrary ratio M of the M-fold expanders (M ≤ K). We propose then a new method of simulation for such HFB A/D converters that avoids any numerical computation of differential equation solutions. The results of simulation are compared with theoretical ones. Moreover, in HFB A/D converter studies, the effect of quantization noise is generally indicated by its average power at the output of the HFB, when it is M-cyclostationary. This paper shows on an example that the variance of the global error at the HFB output can vary a lot in a period of M samples.