Wide-linear-range subthreshold OTA for low-power, low-voltage, and low-frequency applications

We propose a novel configuration of linearized subthreshold operational transcombictance amplifier (OTA) for lowpower, 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 tip 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-mu m, CMOS process. The power consumption of the OTA remains below 1 pW 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.