A low voltage CMOS transresistance-based variable gain amplifier

This paper presents a CMOS realization of a low voltage transresistance amplifier (LVTA) that is capable of operation at a supply voltage as low as 1.5V in a 5V CMOS technology. The circuit employs current feedback to reduce stacking of devices between the supply rails and to lower voltage signal swings, enabling low voltage operation. A R-2R ladder based variable gain amplifier (VGA) designed using the LVTA shows good linearity and a closed loop gain independent of bandwidth. Measured results for a prototype fabricated in a 0.5μ CMOS technology are presented that experimentally demonstrates the proposed approach.