A linear tunable wide input range CMOS OTA

A new technique to realize the linear tunable and wide input range CMOS OTA is proposed. The realization method is achieved by squaring the long tail current (IB) of the differential pair and improved the linear input range by source degeneration technique. The OTA transconductance gain can be linearly tuned from 10nA to 1mA and the linear input-voltage range of about 1Vp with less than 3% nonlinearity is obtained. The performance of the circuit is discussed and confirmed through PSPICE-simulation results in TSMC 0.35 μm CMOS technology with power supply of ±1.5 V.