A 18-22GHz, 13.2mW, 0.22mm2, 5 bit VGA with 15.5dB linear in dB gain control in 130nm SiGe for Satcom on the Move (SOTM) applications

Abstract

This paper proposes a linear in dB variable gain amplifier (VGA) employing a compact topology obtained by modifying the Gillbert Cell. The difference between the quiescent currents of the differential switches stacked over the main transconductor is made to vary exponentially with the controlled current to ensure linear-in-dB control. Single stage is able to provide 15.5dB gain control by biasing the switching transistors through a current DAC exploiting the exponential I-V relationship in BJTs. The presented VGA operating from 18-22GHz outperforms state of the art digitally controlled VGAs in terms of low power consumption (13.2mW) and wide dynamic range (15.5dB, 5-Control bits + 3 Calibration bits) while all other performance metrics like chip area are comparable.