MONOLITHIC CONTINUOUS TIME FILTER

Abstract

Nowadays, a lot of information need to be processed In digital form. However, the transmission between the digital signal and the real world still remain an analog issue, filter acts as one of the Interfacing blocks between them, The figure below shows a typical data acquisition system which Is commonly used In today's circuit. It shows how a filter fits In the Interfacing role In the system. A monollthlc continuous time filter has been studied and Implemented In this project. A Signal Flow Graph was used to describe the signal flow in a passive filter whose component values are derived from filter tables. Typical Data Acquisition system

Analog in -> CTF -> SCF -> ADC -> DSP -> DAC -> CTF/SCF -> Amp -> Analog Out

We have decided to use the transconductor-capacltor filter due to the fact that It can operate at a higher frequency. However, It Is a known fact that a transconductor is not linear In the CMOS Implementation, in this project the anti­ phase common source pair structure was used to increase the linearity.

In order to overcome the process and environmental changes after fabrication, an automatic tuning scheme was Implemented.

The layout is drawn using the Cadence Artist Design Tools, and the GDS2 format Is sent to Orbit Semiconductor for fabrlcatlon.

The prototypes are measured and tested In Institute of Mlcroelectronlcs, NUS.