OTA Slew-Rate and Bandwidth Enhancement Based on Dynamic Input-overdriven Current Mirror

This paper presents a current mirror structure that can improve the performances of the operational amplifiers and comparators, specifically their bandwidth and slew-rate. The current mirror presented in this paper uses a couple of resistors and a coupling capacitor to enhance input current feedthrough while isolating the parasitic capacitance of the diode-mounted transistor. As a result, the majority of the power generated by the input current source is used to overdrive the gate of the output transistor, leading to an increased current mirror gain at high frequency, while preserving the DC unitary gain of the current mirror. The simplicity and effectiveness of this approach make it a valuable enhancement to basic OTAs commonly used in low-power and low-frequency analog building blocks. Simulation results obtained using a 40nm CMOS process demonstrate the efficacy of the slew rate and bandwidth improvement of a basic single-stage OTA.