Log-domain filters based on LC ladder synthesis

A design method is proposed for the synthesis of linear, high-order, continuous-time filters using a unique translinear integrator circuit. Unlike previous attempts at incorporating translinear circuits into filter design, the proposed theory makes explicit use of the exponential nature of the bipolar transistor. This technique is based on the operational simulation of LC ladders. A 5th-order Chebyshev filter is designed, simulated and verified experimentally. The filter shows good amplitude response as well as distortion levels comparable to other filtering schemes.