摘要
This work presents a single-stage operational transconductance amplifier (OTA) with high DC gain for driving nano-farad capacitive loads. The circuit employs two conjugated current mirrors to form high-impedance nodes, enhancing transconductance and driving capability. Flipped-voltage follower (FVF) cells act as variable tail current sources to boost transconductance and generate a dynamic current larger than the bias current during slewing, enabling a faster transient response. The FVFs also allow additional folded drivers on the cascode stage for further improvement. To integrate these techniques, both n- and p-channel differential pairs are used at the input. Implemented in TSMC 0.18-μm CMOS, the OTA achieved a simulated DC gain above 100 dB and a measured gain of 95 dB, validating the proposed design. It shows a unity-gain bandwidth of 5.85 MHz and a slew rate of 0.347 V/μs while driving a 2×4 nF load at 1.8 V.