A 40 MHz 70 dB Gain Variable Gain Amplifier Design Using the gm/ID Design Method

This paper addresses the design and post-fabrication measurements of a 40 MHz CMOS Variable Gain Amplifier (VGA) with a 0 to 70 dB gain control range, using the gm/ID design methodology. The VGA architecture is based on a differential pair stage with an automatic continuous-time offset cancellation circuitry, providing an input offset voltage tolerance up to 50 mV. The 3-stage VGA was designed and fabricated through MOSIS service in an IBM 0.18 μm CMOS process. The VGA dissipates 2.6 mA from a 1.8 V supply, with 34,840 μm2 circuit area, excluding bond-pads.