Abstract: A low voltage, high dc gain and wideband load compensated cascode operational transconductance amplifier (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 bandwidth product of the amplifier is improved from 115 MHz to 194 MHz, the phase margin is also improved from 85 degrees to 95 degrees and the gain is enhanced from 11 dB to 93 dB. This amplifier operates at 2.5 V power supply voltage, drives a capacitive load of 1 pF and gives a power dissipation of 7 mW. The predicted performance is verified by simulations using HSPICE tool with 0.8 /um CMOS AMS parameters.
Key words: Wideband amplifiers, CMOS technology, analog Integrated Circuits, low power, feedforward technique, positive feedback, high dc gain, GBW.