Active and Passive Electronic Components 
Volume 27 (2004), Issue 3, Pages 183-187
doi:10.1080/08827510310001648988

A Current-mode Logarithmic Function Circuit

Muhammad Taher Abuelma'atti and Osama Oglah Faris

 King Fahd University of Petroleum and Minerals, Box 203, Dhahran 31261, Saudi Arabia
Received 18 October 2003; Revised 14 November 2003

Abstract

A new current-mode analog circuit configuration that implements the function ln (x/y) is proposed. The circuit uses bipolar transistors and resistors and is suitable for integration. In the proposed circuit the ratio (x/y) can be larger or smaller than unity. Simulation results are included.