Low-voltage CMOS wideband operational transconductance amplifier with regulated cascode circuit

A low voltage CMOS wideband operational transconductance amplifier (OTA), using regulated cascode structure with an active positive feedback, frequency-dependent current mirrors and feedforward techniques, is presented and analyzed. Such techniques stand as a powerful method of gain, bandwidth, output impedance and phase margin enhancements. In this paper, an efficient implementation of a high output impedance current mirror is used in the design of an OTA by means of the regulated cascode circuits. This amplifier operates at ±1.25 V power supply voltage, exhibits a voltage gain of 68 dB, and provides a gain bandwidth product of 166 MHz. It drives a capacitive load of 1.6 pF and gives a power dissipation of 8.5 mW. The predicted performance is verified by simulations using HSPICE tool with 0.35 μm CMOS TSMC parameters.