Symbolic analysis of the Tau Cell log-domain filter using affine MOSFET models

This paper analyses a filter known as the Tau Cell using symbolic methods and shows that the operation of this filter is independent of the magnitude of the input DC offset. This means that the circuit places no restrictions on whether the input DC offset is a sub-threshold current or not. The circuit behaviour predicted from symbolic analysis was observed in similar circuits on a chip fabricated using MOSIS AMI 1.6 μm technology. This paper highlights the utility of symbolic analysis and shows that it is a powerful tool for circuit analysis and design.