A Wideband dB-Linear VGA With Temperature Compensation and Active Load

In this paper, a wideband accurate dB-linear variable-gain amplifier (VGA) is presented, which consists of three cascading gain stages with dc-offset cancellation. Based on duplicate biasing and active load techniques, this VGA achieves merits such as simple and accurate continuous dB-linear gain control, gain robustness to process and supply voltage variation and constant bandwidth at different gain settings. The dB-linear gain control is realized based on exponential current steering. The exponential conversion can be based on bipolar transistors or MOS transistors in subthreshold region. Both ways are implemented in this design for comparison purpose. With temperature compensation circuit, this VGA is insensitive to temperature variation. All gain stages of the VGA share the same biasing, exponential V-I conversion and temperature compensation circuits to reduce design complexity. This proposed VGA is fabricated in 55-nm CMOS technology with a core area of 0.033 mm2. The measurement results show the proposed VGA has a dB-linear gain-control range from −37dB to 14 dB with an error within 0.65 dB. The −3dB bandwidth of the VGA is 740 MHz and is nearly constant when the gain varies. The core VGA circuit consumes about 2.49 mW. The proposed design features wide bandwidth, small chip area, and low power consumption.

[1]  B. Razavi,et al.  - Gb / s Limiting Amplifier and Laser / Modulator Driver in 0 . 18-m CMOS Technology , 2001 .

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

[3]  K. Sakui,et al.  A CMOS bandgap reference circuit with sub-1-V operation , 1999 .

[4]  Pui-In Mak,et al.  A Wideband Inductorless dB-Linear Automatic Gain Control Amplifier Using a Single-Branch Negative Exponential Generator for Wireline Applications , 2018, IEEE Transactions on Circuits and Systems I: Regular Papers.

[5]  Kaixue Ma,et al.  Temperature-Compensated dB-linear Digitally Controlled Variable Gain Amplifier With DC Offset Cancellation , 2013, IEEE Transactions on Microwave Theory and Techniques.

[6]  Andrea Mazzanti,et al.  5.6 A 420µW 100GHz-GBW CMOS Programmable-Gain Amplifier leveraging the cross-coupled pair regeneration , 2016, 2016 IEEE International Solid-State Circuits Conference (ISSCC).

[7]  Yong-Zhong Xiong,et al.  A 5-Gb/s Automatic Gain Control Amplifier With Temperature Compensation , 2012, IEEE Journal of Solid-State Circuits.

[8]  Xiao Peng Yu,et al.  A wideband BiCMOS variable gain amplifier with novel continuous dB-linear gain control and temperature compensation , 2017 .

[9]  Sang-Gug Lee,et al.  A Binary-Weighted Switching and Reconfiguration-Based Programmable Gain Amplifier , 2009, IEEE Transactions on Circuits and Systems II: Express Briefs.

[10]  Chul Soon Park,et al.  A 2.16 mW Low Power Digitally-Controlled Variable Gain Amplifier , 2010, IEEE Microwave and Wireless Components Letters.

[11]  Xiaofeng He,et al.  Cell-Based Variable-Gain Amplifiers With Accurate dB-Linear Characteristic in 0.18 µm CMOS Technology , 2015, IEEE Journal of Solid-State Circuits.

[12]  Songcheol Hong,et al.  A Wideband CMOS Variable Gain Amplifier With an Exponential Gain Control , 2007, IEEE Transactions on Microwave Theory and Techniques.

[13]  B. Razavi,et al.  10-Gb/s limiting amplifier and laser/modulator driver in 0.18-μm CMOS technology , 2003, IEEE J. Solid State Circuits.

[14]  Xiang Yi,et al.  A Wideband Analog-Controlled Variable-Gain Amplifier With dB-Linear Characteristic for High-Frequency Applications , 2016, IEEE Transactions on Microwave Theory and Techniques.

[15]  A. Tekin,et al.  A Differential-Ramp Based 65 dB-Linear VGA Technique in 65 nm CMOS , 2009, IEEE Journal of Solid-State Circuits.

[16]  Xiao Peng Yu,et al.  An Accurate dB-Linear CMOS VGA Based on Double Duplicate Biasing Technique , 2018, IEEE Solid-State Circuits Letters.

[17]  Bumman Kim,et al.  Accurate dB-Linear Variable Gain Amplifier With Gain Error Compensation , 2013, IEEE Journal of Solid-State Circuits.

[18]  F. Xavier Moncunill-Geniz,et al.  Baseband Superregenerative Amplification , 2009, IEEE Transactions on Circuits and Systems I: Regular Papers.

[19]  Kaixue Ma,et al.  A 7.9-mW 5.6-GHz Digitally Controlled Variable Gain Amplifier With Linearization , 2012, IEEE Transactions on Microwave Theory and Techniques.

[20]  S. Kang,et al.  A Precise Decibel-Linear Programmable Gain Amplifier Using a Constant Current-Density Function , 2012, IEEE Transactions on Microwave Theory and Techniques.

[21]  D. Coffing,et al.  A variable gain amplifier with 50 dB control range for 900 MHz applications , 2001, Proceedings of the 2001 BIPOLAR/BiCMOS Circuits and Technology Meeting (Cat. No.01CH37212).

[22]  G. Takemura,et al.  A low-power low-noise accurate linear-in-dB variable-gain amplifier with 500-MHz bandwidth , 2000, IEEE Journal of Solid-State Circuits.