Multiple-input translinear element log-domain filters

I describe the implementation of log-domain filters with multiple-input tra nslinear elements (MITEs), Such circuit elements produce output currents th at are exponential in a weighted sum of their input voltages. I discuss the operation of the MITE building block circuit from which I construct MITE l og-domain filters. Then, I analyze the behavior of a first-order low-pass M ITE log-domain filter, the simplest such circuit. I also present a fully tu nable second-order low-pass MITE log-domain biter I show experimental measu rements of a version of the second-order filter that was fabricated in a 1. 2-mum double-poly CMOS process with an npn bipolar option. I also describe a simple procedure for synthesizing MITE log-domain filters from state-spac e descriptions. We can obtain such state-space descriptions from a variety of sources; the procedure that I describe can be used regardless of the sou rce of the description. We can often derive such descriptions conveniently from already extant filters that have been previously implemented within a different class of filters. I shall illustrate the synthesis procedure by d eriving two simple MITE log-domain filters from single-ended voltage-mode o perational transconductance amplifier C filter prototypes.