Wideband variable-gain amplifiers based on a pseudo-current-steering gain-tuning technique

• Main Authors: Kong, Lingshan, Chen, Yong, Yu, Haohong, Pan, Quan, Boon, Chirn Chye, Mak, Pui-In, Martins, Rui P.
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2020
• Subjects: Engineering::Electrical and electronic engineering; Variable-gain Amplifier (VGA); CMOS
• Online Access: https://hdl.handle.net/10356/141095
• Institution: Nanyang Technological University

This paper reports two variable-gain amplifiers (VGAs) featuring a new pseudo-current-steering gain-tuning technique. In the first VGA (VGA-I), a single-voltage-controlled dual-branch current mirror is exploited as a standalone gain control block. In the second VGA (VGA-II), two NMOS transistors, which are biased by a tunable voltage, are integrated into a conventional common-source amplifier to steer away partial of the total current. Fabricated in 40-nm CMOS technology, the VGA-I (VGA-II) occupies a tiny area of 0.03 mm 2 (0.024 mm 2 ) and consumes 22 mW (20 mW). Measured over a gain range of > 64 dB, the -3-dB bandwidth of the VGA-I (VGA-II) is 9 GHz (6.6 GHz). For the time-domain tests, VGA-I (VGA-II) exhibits a jitter of 40 ps (30 ps), under a 2 7 -1 PRBS input at 12 Gb/s. Their power efficiencies (1.83 and 1.67 pJ/bit) compare favorably with state-of-the-art wideband VGAs.