Design of high frequency OTA-C filters utilizing optimization techniques

number: 
40
English
Degree: 
Author: 
Intisar Abdul Majied Abdul Saiyd
Supervisor: 
Dr. Fawzi M. Al-Naima
year: 
1992
Abstract:

The aim of the presented project is to design high frequency active filters based on the use of operational transconductance amplifiers (OTAs). These devices have gained considerable attention over the last decade as they are increasingly replacing operational amplifiers in analog signal processing applications and active filter design because of their good features especially the high frequency operation. However, the imperfection parameters of OTA device affect the behavior of structures based on it. The frequency limitations are studied in this thesis, and it has been shown that the excess phase due to the finite transconductance bandwidth gives the dominant parasitic effect, hence, has paid a particular interest at design stage. A computer-aided optimization procedure is presented for the design of second-order OTA-C filter structures taking into account the linear nonideal transconductance model approximated with one or two pole models. The objective is to determine the values of design parameters that satisfy filter requirements with minimum effect of parasitic poles that exist in addition to the required pole pair as a result of frequency limited transconductance gain of actual OTA. Constrained optimization of Complex method is used successfully for this purpose and the pole locations on the complex S-plane before and after design procedure are determined to give an impression on the stability conditions and show the displacement of the dominant poles due to the presence of parasitic poles.The programs are written in Turbo Pascal that offers rich data types and powerful computational and graphical procedures and functions. The simulated results are obtained with PSPICE program to show design feasibility.