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 co...

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Bibliographic Details
Published in:IEEE transactions on circuits and systems. I, Regular papers Regular papers, 2019-09, Vol.66 (9), p.3279-3287
Main Authors: Song, Xiong, Lu, Zhenghao, Cai, Liying, Yu, Xiao-Peng, Yeo, Kiat-Seng, Chen, Jer-Ming
Format: Article
Language:English
Subjects:
Active load
Amplification
Bandwidth
Bandwidths
Bipolar transistors
Broadband
Circuit design
CMOS
Conversion
dB-linear
Gain
Gain control
MOS devices
Power consumption
Robust control
Robustness
Semiconductor devices
Steering
Temperature compensation
Topology
Transistors
Tuning
Variable gain
variable-gain amplifier
Voltage control
wideband
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Summary: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 mm 2 . 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.
ISSN:1549-8328
1558-0806
DOI:10.1109/TCSI.2019.2924667