A High-Speed Fully Differential Telescopic Op-Amp for Active Filter Designs in V2X Applications

Abstract

In this paper, an ultra-wideband fully differential two-stage telescopic 65-nm CMOS op-amp is presented, which uses low-voltage design techniques such as level shifter circuits and low-voltage cascode current mirrors. The designed op-amp consists of two stages. While the telescopic first stage provides high speed and low swing, the second stage provides high gain and large swing. Common-mode feedback circuits (CMFB), which contain five transistors OTA and sensing resistors, are used to set the first-stage output to a known value. The designed two-stage telescopic operational amplifier has 41.04[Formula: see text]dB lower frequency gain, 1.81[Formula: see text]GHz gain-bandwidth product (GBW) and 51.9∘ phase margin under 5[Formula: see text]pF load capacitance. The design consumes a total current of 11.9[Formula: see text]mA from a 1.2-V supply voltage. Presented fully differential two-stage telescopic op-amp by using low-voltage design techniques is suitable for active filter in vehicle-to-everything (V2X) applications with 120[Formula: see text][Formula: see text]m[Formula: see text]m layout area.