OTA-C Implementation of Fractional-Order Lead/Lag Compensators

A novel topology that approximates the behavior of fractional-order lead/lag compensators is introduced in this work. This is achieved using the Pade’ approximation of the function of the lead/lag compensator by a rational integer-order function. Thanks to the employment of Operational Transconductance Amplifiers as active elements, the proposed scheme offers the benefit of electronic tuning capability of the characteristics of the compensator. In addition, the presented scheme is capable of implementing both types of compensators using the same topology. The performance of the proposed topology is evaluated using the Cadence software and MOS transistor models provided by the Austria Mikro Systeme 0.35μm CMOS process.