Cell-based variable-gain amplifiers with accurate dB-linear characteristic in 0.18 µm CMOS technology

• Main Authors: Liu, Hang, Zhu, Xi, Boon, Chirn Chye
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2015
• Subjects: DRNTU::Engineering::Computer science and engineering::Hardware::Integrated circuits
• Online Access: https://hdl.handle.net/10356/106706; http://hdl.handle.net/10220/25126; http://dx.doi.org/10.1109/JSSC.2014.2368132
• Institution: Nanyang Technological University

A simple and robust “cell-based” method is presented for the design of variable-gain amplifiers (VGAs). The proposed unit cell utilizes a unique gain compensation method and achieves accurate dB-linear characteristic across a wide tuning range with low power consumption and wide bandwidth. Several such highly dB-linear unit cells can be cascaded to provide the required gain range for a VGA. To prove the concept, single-cell, 5-cell, 10-cell and 15-cell reconfigurable VGAs were fabricated in a standard 0.18 μm CMOS technology. The measurement results show that the 10-cell VGA achieves a gain range of 38.6 dB with less than 0.19 dB gain error. The 15-cell VGA can either be used as reconfigurable VGA for analog control voltage or tunable PGA for digital control stream, with the flexibility of scaling gain range, gain error/step and power consumption. For the VGA at highest gain setting, it consumes 1.12 mW and achieves a gain range of 56 dB, gain error less than 0.3 dB.