A Linear-in-Decibel Automatic Gain Control Amplifier With Dual Mode Continuous Gain Tuning

A reconfigurable fully integrated automatic gain control (AGC) amplifier is presented which is based on a dual mode continuous gain adjustment variable-gain amplifier (VGA). The VGA is realized based on the current-steering structure, achieving a linear-in-dB gain tuned by AGC's feedback voltage. A current division active load is proposed, which provides additional gain control range and realizes gain robustness to process and supply variations without extra calibration. Simulated with Cadence IC, the maximum gain variations due to process and supply variations are 3.5 dB and 2.6 dB, respectively. By using dual mode gain tuning technique, the VGA achieves a total gain range of 68.2 dB. Both bandwidth and gain of the VGA are adjusted independently. The AGC is realized in UMC 55-nm CMOS technology with 0.026 mm(2) core area. With the current division ratio K of 0.5, the proposed VGA achieves a linear-in-dB gain of 42.2 dB ( -30.0 to 12.2 dB) with less than 0.79 dB error. The -3 dB bandwidth can be adjusted from 80 MHz to 140 MHz and is insensitive to gain variations. The power dissipation is from 2.9 mW to 4.5 mW. This design features bandwidth scalability and the gain independent of bandwidth to achieve various applications.

Automated summary

This paper presents a reconfigurable fully integrated automatic gain control (AGC) amplifier based on a dual mode continuous gain adjustment variable-gain amplifier (VGA). The VGA is implemented using a current-steering structure to achieve linear-in-dB gain tuning. A current division active load is proposed to provide additional gain control range and gain robustness. The proposed VGA achieves a total gain range of 68.2 dB and independent adjustment of bandwidth and gain. The AGC is implemented in UMC 55-nm CMOS technology with a core area of 0.026 mm².