A Review of CMOS Variable Gain Amplifiers and Programmable Gain Amplifiers

ABSTRACT

CMOS implementations of variable gain amplifiers (VGAs) and programmable gain amplifiers (PGAs) are reviewed in this paper. They fall into two categories: Radio Frequency VGA/PGAs and Intermediate Frequency VGA/PGAs. Most approaches to realize gain tuning create linear VGAs and consequently exponential conversion are required. The CMOS circuit realizations of exponential converters are complex and are also reviewed. In contrast, PGAs benefit from their flexible gain control mode and hence have much simpler structures. However, lower distortions and higher gain accuracy can be achieved for PGAs. Therefore, PGAs are preferred in most scenarios. This paper also presents a CMOS Gilbert VGA and a novel high linearity constant bandwidth PGA with improved common mode rejection. The DC-offset cancellation methods are reviewed as well. Finally, trends of VGAs/PGAs in modern receivers are analysed.

KEYWORDS:

• Analog integrated circuits
• CMOS integrated circuits
• Feedback circuits
• Linear circuits
• PGA
• Receivers
• VGA

ORCID

Chunfeng Bai http://orcid.org/0000-0002-3149-7780 Jianhui Wu http://orcid.org/0000-0002-7878-498X

Additional information

Funding

This work was supported by The National Natural Science Foundation of China under the project number of 61401090 and 61574035.

Notes on contributors

Chunfeng Bai

Chunfeng Bai was born in Jiangsu, China, in 1987. He received the MS degree in Micro-electronics from Southeast University, Nanjing, China, in 2013. Presently, he is working towards the PhD degree in the department of National ASIC system engineering research centre. His research interest is in the field of analogue CMOS integrated circuits such as VGAs andfilters. Email: [email protected]

Jianhui Wu

Jianhui Wu was born in Anhui, China, in 1966. He received the MS and PhD degrees from Southeast University, Nanjing, China, in 1992 and 2000 respectively, both in electronic engineering. He is now a Professor in National ASIC system engineering research centre, Southeast University, Nanjing. His research interests include RF IC design and mix-signal IC design.

Xiaoying Deng

Xiaoying Deng was born in 1982 and received the MS and PhD degree in Microelectronic and Solid State Electronic from Southeast University in 2008 and 2012. She is now a lecturer in Shenzhen Key Lab of Advanced Communications and Information Processing, Shenzhen University. Her interests include VLSI circuit design, ring oscillator, and ADPLL design. Email: [email protected]