A Pre-distortion Technique for OTA-C Filter Design

Abstract

The growing demand of continuous filters in portable electronic equipment, wireless receivers and continuous-time (CT) analog-to-digital converters (ADCs) has spawned a strong research interest from industry and academia. Gm -C filters are one of the most widely used continuous time filters because Gm -C filters are one of the fastest active integrators and enable low-power operation and tuning of the filter characteristics at higher frequencies. However issues concerning non-idealities which are parasitic conductance and capacitance in OTA and lossiness in reactance elements are less addressed. In this thesis a novel predistortion technique for synthesizing OTA-C filters is presented. The synthesis algorithm makes it possible to design a Butterworth or Chebychev filter which offsets non-idealities of the OTA. This approach substantially relieves the complexity of existing lossy ladder synthesis algorithms, and makes the synthesis of lossy ladder filters more reliable for practical applications.