Distortion analysis of high-frequency log-domain filters using Volterra series

An approach to estimate the distortion in log-domain filters is presented. The models used for the bipolar transistors include the C_π and C_sub parasitic capacitors, the beta effect, and the parasitic emitter resistances. Simple closed-form expressions describing the effect of each nonideality on distortion are derived and compared to simulations. A general method, which could be extended to analyze higher order filters, based on Volterra series, is used.