Low-Voltage LowPower High Gain CMOS OTA using Active Positive Feedback with Feedforward and

Abstract: A low voltage, high dc gain and wideband load compensated cas-code operational transconductance amplier (OTA), using an active positive feedback with feedforward technique and frequency-dependent current mirrors (FDCM), is presented and analyzed. Such techniques stand as a powerful method of gain, bandwidth and phase margin enhancements. In this paper, a frequency-dependent current mirror, whose input impedance increases with frequency, is used to form the feedforward path at the input of the current mirror with a feedforward capacitor. By using these techniques, the gain band-width product of the amplier is improved from 115 MHz to 194 MHz, the phase margin is also improved from 85 Æ to 95 Æ and the gain is enhanced from 11 dB to 93 dB. This amplier operates at 2.5 V power supply voltage, drives a capacitive load of 1pF and gives a power dissipation of 7 mW. The predicted performance is veried by simulations using HSPICE tool with 0.8 m CMOS AMS parameters