A Second-Order Log-Domain Bandpass Filter for Audio Frequency Applications

Abstract— Log-domain filters have recently come into the limelight of the VLSI community as an important class of circuits for implementing continuous-time filters in the current domain [4], [3], [2]. Some papers have discussed log-domain circuit analysis [1] and some have addressed circuit synthesis [2], [5], [6], [7]. In this paper we describe synthesis of a secondorder log-domain bandpass filter, address issues related to lowfrequency (audio-frequency) filter design, and show experimental results from a system fabricated in a standard 2 μm BiCMOS technology.