The synthesis of second order programmable and electronically tunable universal filter in the log domain

Abstract

In this paper, a low voltage and electronically tunable Class AB differential type universal filter is synthesized in the log domain. The high pass, band pass and low pass frequency characteristics can be obtained by programming some current sources. The filter's Q quality factor and natural frequency could be tuned by varying the currents of the current sources. The second order log domain filter is synthesized in the state space. The proposed universal filter with 1.5 V voltage source is simulated in PSpice for ideal and CBIC-R type transistors. By varying the values of the current sources, the natural frequency is swept for 50kHz-5MHz and Q quality factor is tuned for 0.707-5 electronically. The obtained simulation results are given. © 2005 IEEE.