Analysis and compensation of log-domain filter deviations due to transistor nonidealities

Log-domain filters have recently received considerable research attention as an intriguing alternative to the existing continuous-time filter implementations. Log-domain filtering explicitly employs the diode nature of bipolar transistors, resulting in a class of frequency-shaping translinear circuits. It demonstrates potential in high-speed and low-power applications. Most interesting of all, it opens the door to elegantly realizing a linear system with inherently non-linear (logarithmic-exponential) circuit building blocks, and may benefit from the advantages offered by companding signal processing.;However, log-domain filters suffer directly from transistor-level nonidealities. This thesis will study the filter response deviations due to major transistor imperfections, which include parasitic emitter and base resistances, finite beta, Early effect, and area mismatches. SPICE simulations, both large and small-signal analysis, are performed to verify the results. By understanding the underlying deviation mechanisms, very natural and simple electronic compensation methods are proposed. The analysis will cover both biquadratic and high-order ladder log-domain filters.