A 35-mW 30-dB Gain Control Range Current Mode Linear-in-Decibel Programmable Gain Amplifier With Bandwidth Enhancement

This paper presents the design of a programmable gain amplifier (PGA) that serves as an interface between the receiver front-end and the baseband processor. The proposed PGA design is fabricated in a commercial 0.18-mu m SiGe BiCMOS process with a topology consisting of two digitally variable gain amplifiers cascaded by a post amplifier and interconnected by differential wideband matching networks that presents an overall enhanced gain bandwidth product. By using the current mode exponential gain control technique, the proposed design achieves a broad 30-dB linear-in-decibel gain range, a gain-independent output 1-dB compression point better than -10 dBm, input/output return loss better than 13 dB, a +/- 0.75-dB gain flatness over a multi-decade frequency range from 2.5 MHz to 1.17 GHz, a measured in-band group-delay variation of 30 ps, a 35-mW power consumption, and a 0.25-mm(2) core die area.