A CMOS IF Variable Gain Amplifier with Exponential Gain Control

Sungwoo CHA  Tetsuya HIROSE  Masaki HARUOKA  Toshimasa MATSUOKA  Kenji TANIGUCHI  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E88-A   No.2   pp.410-415
Publication Date: 2005/02/01
Online ISSN: 
DOI: 10.1093/ietfec/e88-a.2.410
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
Category: 
Keyword: 
variable gain amplifier,  VGA,  linearized transconductance,  linear-in-dB characteristics,  exponential gain control,  CMOS,  

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Summary: 
An intermediate frequency (IF) variable gain amplifier (VGA) with exponential gain control for a radio receiver is fabricated in 0.25-µm CMOS technology. The techniques to improve the bandwidth and to reduce temperature dependence of gain are described. The complete VGA is composed of two stages of linearized transconductance VGA and three stages of fixed gain amplifier (FGA). The complete VGA provides a continuous 10 dB to 76.5 dB gain control range, an IIP3 of -11.5 dBm and an NF of 15 dB at 40 MHz.