Low-Voltage Low-Power CMOS Rail-to-Rail Voltage-to-Current Converters

This paper presents three compact CMOS voltage-to-current converters based on OTA/common-source configurations, which attain rail-to-rail input-output operation. The three converters present a high impedance input node while provide a highly linear V-I relationship over a (-40, +120 degrees C) temperature range with a maximum transconductance temperature coefficient of 175 ppm/degrees C. Measurement results for 1.2-V 0.18-mu m CMOS implementations confirm rail-to-rail operation with bandwidths of up to 14.5 MHz and THD of up to -50 dB for 1 V-pp at 100 kHz, active areas below 0.0145 mu m(2) and power consumption below 85 mu W, which make these basic building blocks suitable for portable applications.