Title :
A low-voltage CMOS exponential function circuit for AGC applications
Author :
Lin, Chi-Hung ; Pimenta, Tales C. ; Ismail, Mohammed
Author_Institution :
Dept. of Electr. Eng., Ohio State Univ., Columbus, OH, USA
fDate :
30 Sep-3 Oct 1998
Abstract :
This paper describes how to implement a CMOS exponential function circuit, which can be used for Automatic Gain Control (AGC) and Variable Gain Amplifiers (VGA). The proposed exponential function circuit is based on Taylor´s series expansion, and it has been implemented using a V-I converter and a squarer circuit, both obtained from the same core cell. The first order term of Taylor´s series is implemented by a constant bias current. The low-voltage (⩽3 V) low power CMOS core cell has an almost rail-to-rail differential-input swing. In the entire voltage control range, the dB-linear function achieves a 30 dB linear range. For a 20 dB range, the linearity error is less than ±0.5%
Keywords :
CMOS analogue integrated circuits; amplifiers; analogue processing circuits; automatic gain control; low-power electronics; series (mathematics); AGC applications; LV exponential function circuit; Taylor series expansion; V-I converter; constant bias current; dB-linear function; low power CMOS core cell; low-voltage CMOS circuit; rail-to-rail differential-input swing; squarer circuit; variable gain amplifiers; CMOS technology; Circuits; Electronic equipment; Gain control; Linearity; Power supplies; Taylor series; Threshold voltage; Very large scale integration; Voltage control;
Conference_Titel :
Integrated Circuit Design, 1998. Proceedings. XI Brazilian Symposium on
Conference_Location :
Rio de Janeiro
Print_ISBN :
0-8186-8704-5
DOI :
10.1109/SBCCI.1998.715440
