A low-power CMOS VGA with 60-dB linearly controlled gain range for GPS application

In this paper, a low-power CMOS variable gain amplifier (VGA) with dB-linear gain, which is based on an approximated exponential equation is presented. Being designed for GPS application, the proposed VGA is composed of two cascaded variable gain stages and a fixed gain stage, and has advantages of low-power, wide controlled-gain-range and highly-linear. The VGA is implemented in 0.18 ¿m CMOS technology. The simulations show that a total linear gain range of 60 dB (27 dB-87 dB) with 3-dB bandwidth can be obtained at 16 MHz; the IIP3 varies from -11 dBm (at the minimum gain) to -60 dB (at the maximum gain). The power dissipation is less than 2 mA from a 1.8 V supply, and the input referred noise voltage is only 13 ¿Vrms (at the 55 dB gain).

[1]  Takafumi Yamaji,et al.  A Temperature Stable CMOS Variable Gain Amplifier with 80-dB Linearly Controlled Gain Range , 2001 .

[2]  Trung-Kien Nguyen,et al.  CMOS exponential current-to-voltage circuit based on newly proposed approximation method , 2004, 2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512).

[3]  Willy Sansen,et al.  An integrated wide-band variable-gain amplifier with maximum dynamic range , 1974 .

[4]  Quoc-Hoang Duong,et al.  A 95-dB linear low-power variable gain amplifier , 2006, IEEE Transactions on Circuits and Systems I: Regular Papers.

[5]  Shen-Iuan Liu,et al.  CMOS current-mode exponential-control variable-gain amplifier , 2001 .

[6]  C.W. Mangelsdorf.  A variable gain CMOS amplifier with exponential gain control , 2000, 2000 Symposium on VLSI Circuits. Digest of Technical Papers (Cat. No.00CH37103).

[7]  Quoc-Hoang Duong,et al.  An all CMOS 84dB-linear low-power variable gain amplifier , 2005, Digest of Technical Papers. 2005 Symposium on VLSI Circuits, 2005..