Wide-Linear-Range Subthreshold OTA for Low-Power, Low-Voltage, and Low-Frequency Applications

We propose a novel configuration of linearized subthreshold operational transconductance amplifier (OTA) for low-power, low-voltage, and low-frequency applications. By using multiple input floating-gate (MIFG) MOS devices and implementing a cubic-distortion-term-canceling technique, the linear range of the OTA is up to 1.1 Vpp under a 1.5-V supply for less than 1% of transconductance variation, according to testing results from a circuit designed in a double-poly, 0.8- , CMOS process. The power consumption of the OTA remains below 1 for biasing currents in the range between 1–200 nA. The offset voltage due to secondary effects (contributed by parasitic capacitances, errors and mismatches of parameters, charge entrapment, etc.) is of the order of a few ten millivolts, and can be canceled by adjusting biasing voltages of input MIFG MOS transistors.