A Very Linear OTA with V-I Conversion based on Quasi-Floating MOS Resistor

This paper proposes a novel very linear tunable transconductor based on local feedback loops. The linear V-I conversion is accomplished using MOS resistors based on quasi-floating gate transistors. The absence of current mirrors in the signal path provides low sensitivity to transistor mismatch and decrease of nonlinear distortion. The OTA was designed in a 0.5 μm CMOS technology with ±1.65-V supply voltage. Simulation results show a THD of -80 dB at 100 kHz with 1 Vpp input signal. Good linearity of the OTA over a large tuning range is obtained.