A Low Power CMOS Wideband Variable Gain Amplifier

C.-C. Sung, M.-F. Chou, and K.-A. Wen (Taiwan)


Variable gain amplifier, pseudo-exponential.


A CMOS variable gain amplifier (VGA) with a wide gain control range is presented. The amplifier consists of a source-coupled pair with diode connected loads and a pseudo-exponential gain control circuit. The gain is obtained by a novel wide-range pseudo-exponential circuit topology. The proposed VGA was implemented in 0.18m CMOS process which exhibits a 90-dB gain control range. The VGA draws 1.87 mW power from a 1.8-V supply per stage. Its wide bandwidth reveals that this design is well suited for wideband applications as 802.15.3a.

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