Temperature-compensated dB-linear digitally controlled variable gain amplifier with DC offset cancellation

• Main Authors: Kumar, Thangarasu Bharatha, Ma, Kaixue, Yeo, Kiat Seng
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Antennas, wave guides, microwaves, radar, radio
• Online Access: https://hdl.handle.net/10356/99419; http://hdl.handle.net/10220/17615
• Institution: Nanyang Technological University

This paper presents a compact digitally controlled variable gain amplifier (DVGA) with capabilities of both temperature compensated linear-in-decibel (dB-linear) gain control and DC offset cancellation (DCOC) without making use of either the feedback or the feed-forward loop. The proposed DVGA design is a 3 stage inductorless cascaded amplifier that is integrated with a temperature compensated dB-linear gain control, a DCOC, an output common mode feedback (CMFB), a 6-bit digital gain control (with a 64 step resolution), a power shutdown mode, and a linearizer for improving the 1-dB gain compression point. The design is fabricated using a commercial 0.18-m SiGe BiCMOS technology. The DVGA has a measured gain range of 18.4 dB with an average step size of 0.3 dB, a 3-dB bandwidth from 2 MHz to 1.9 GHz with a ±0.75 dB gain flatness from 2.75 MHz to 1.2 GHz, an input 1-dB gain compression point better than -12.5 dBm, an input return loss better than 12 dB, an output return loss better than 16 dB, and a DC power consumption of 12.2 mW from a 1.8 V supply.