OTA-C Filters

Abstract

In this chapter, the realization of filters using operational transconductance amplifiers (OTA) is considered. Building blocks such as OTA-C integrators, OTA-C differentiators, and first-order low-pass, high-pass, and all-pass OTA-C filters are described. Circuits with current/voltage input/output are considered. The use of dual current output OTAs is also studied. The realization of second-order voltage and current mode filters based on Tarmy–Ghausi active RC configuration as well as two integrator loop has been presented in detail. The design of ladder filters using simulated inductors and FDNRs is considered. The technique for high-order current-mode OTA-C filters based on coupled biquads is also described. In addition, the use of analytical synthesis technique to derive multiloop feedback type OTA-C filters is described. The effect of OTA nonidealities using pole-zero model as well as finite output resistance and capacitance of the OTAs on chosen filter configurations are presented. Structures for OTA-C oscillators are also presented. Noise analysis techniques and estimation of distortion are also described. SPICE simulation examples are given in order to illustrate certain ideas.