The design of a transconductor circuit for Gm-C filters.

摘要

The trend in modern integrated circuits is to incorporate as many building blocks as possible in a single chip ultimately towards a complete system on chip. This trend is motivated by the advances in the CMOS integrated circuit technology. Analog continuous time filters are a basic building block in many electronic systems. So, this trend also increases the need for continues-time filters that can be fully integrated on chips using CMOS technology for essential applications such as anti-aliasing and reconstruction. Those filters should be able to operate at higher frequencies and at low supply voltages.;Gm-C filters are the most common continuous-time analog filters used for fully monolithic integration on chip today. The Gm-C technique uses transconductors (Gm) and capacitors (C) to realize monolithic active filters. The transconductor is the main building block of Gm-C filters. While there are many reported circuit techniques for realizing transconductors, their main limitation is their limited input signal swing and poor linearity. Moreover, most techniques are not compatible with very low power supply operation.;This thesis reports the circuit level implementation of a transconductor cell that is intended to be used in open loop configuration for the design of Gm-C filters in standard CMOS technology. The circuit tries to overcome the limitations of current techniques.;The transconductor cell was fabricated in 0.35mum TSMC CMOS technology. The design of the highly linear, tunable, pseudo differential transconductor circuit will be discussed. The predicted post-layout simulation results and test-chip experimental results are discussed and compared.