Very High-Gain and Fast-Settling Opamp for Switched-Capacitor Applications

A high gain, high frequency single stage CMOS opamp is designed and simulated. The authors used gain boosting technique and common mode feedback circuitry on a differential input/output 0.35&3x003Bc;m CMOS amplifier. Results comprehend a DC gain of 100 dB, a unity-gain frequency superior to 400 MHz associated with a phase margin in the range of 70 degrees. Good insensitivity to temperature, process and common mode input voltage variations has been demonstrated.