Rail-to-rail tunable CMOS V-I converter

Abstract

A novel technique is proposed to achieve highly linear programmable voltage-to-current (V-I) converters over a rail-to-rail input range. It employs two passive resistors with one of their terminals tied to a very low impedance node to achieve an almost distortionless V-I conversion for rail-to-rail input signals. The resistor currents are conveyed to the output via programmable floating-gate MOS current mirrors that work in moderate inversion, thus achieving transconductance tuning in a wide range while preserving linearity in the rail-to-rail input range. Initial charge of the floating gates is removed during fabrication. An implementation fabricated in a 0.5-/spl mu/m CMOS technology using a dual supply of /spl plusmn/1.5 V achieves a THD of -60 dB over a wide transconductance tuning range with differential input swings equal to the total supply voltage. The area and power consumption are 0.1 mm/sup 2/ and 2.6 mW.