Low-power class-AB CMOS voltage feedback current operational amplifier with tunable gain and bandwidth

Abstract

A CMOS class AB variable gain Voltage Feedback Current Operational Amplifier (VFCOA) is presented. The implementation is based on class AB second generation current conveyors and exploits an electronically tunable transistorized feedback network. The circuit combines high linearity, low power consumption and variable gain range from 0 to 24 dB with nearly constant bandwidth, tunable from 1 to 3 MHz. A prototype has been fabricated in a 0.5-um technology and occupies a total area of 0.127 mm2. The VFCOA operates using a 3.3-V supply with static power consumption of 280.5 uW. Measurements for maximum gain configuration show a dynamic range (1% THD@300kHz) of 87.5 dB and a THD lower than -40dB for an output current 23 times the bias current.