A 48-dB dynamic gain range/stage linear-in-dB low power Variable Gain Amplifier for direct-conversion receivers

In this paper, a low power Variable Gain Amplifier (VGA) circuit with an approximation to exponential gain characteristic is presented. It is achieved using current mirrors to generate appropriate current signals to bias the input stage of the VGA circuit working in triode region, and the output stage working in saturation region, respectively. The VGA circuit presented herein comes with a 549 μW maximum power consumption given a 1.8 V supply, and most important of all, it has a linear-in-dB 48-dB dynamic gain range per stage. The effect of the input trasconductance and the output resistance on the linearity of gain control is also discussed. This circuit is fabricated using a 0.18 μm standard CMOS process with a core area of 0.0045 mm2.

[1]  Ian F. Akyildiz,et al.  Wireless sensor networks: a survey , 2002, Comput. Networks.

[2]  Qizheng Gu,et al.  RF System Design of Transceivers for Wireless Communications , 2005 .

[3]  Chorng-Kuang Wang,et al.  A 3.3-V CMOS wideband exponential control variable-gain-amplifier , 1998, ISCAS '98. Proceedings of the 1998 IEEE International Symposium on Circuits and Systems (Cat. No.98CH36187).

[4]  Shen-Iuan Liu,et al.  A 0 . 18-m CMOS 1 . 25-Gbps Automatic-Gain-Control Amplifier , 2009 .

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

[6]  Shen-Iuan Liu,et al.  A 0.18-$\mu{\hbox {m}}$ CMOS 1.25-Gbps Automatic-Gain-Control Amplifier , 2008, IEEE Transactions on Circuits and Systems II: Express Briefs.

[7]  J. M. Khoury,et al.  On the design of constant settling time AGC circuits , 1998 .

[8]  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).