Minimum parasitic effects biquadratic OTA-C filter architectures

Abstract

This paper presents a systematic analysis to determine the tuning range limitations of biquadratic OTAC filter architectures, as well as a strategy for the selection of minimum parasitic effects filter structures for a given transfer function (filter type). The analysis uses an OTA macromodel that includes finite input and output impedances along with frequency-dependent transconductance. Experimental data of the macromodel parameters of real OTAs along with analytical results are used to estimate the practical tuning (bounds) limitations of the different biquadratic filter structures. Some of the available transfer functions from these filter architectures present minimum parasitic effects. Experimental results from CMOS chip tests showed agreement with the minimum parasitic effects theoretical results.