Schmitt Trigger Based Single-Ended Voltage Amplifier with Positive Feedback Control for Ultra-Low-Voltage Supplies
Abstract
This work presents a Schmitt trigger based pseudo-differential single-ended voltage amplifier using a Schmitt trigger inverter cell in parallel with a push-pull inverter cell to eliminate hysteresis and improve voltage gain for ultra-low-voltage supplies. Positive feedback is controlled by changing independently the Schmitt trigger and push-pull cells body input terminal voltages, which enables high voltage gain operation without hysteresis for supply voltages as low as 200 mV and as high as 500 mV. A prototype was fabricated for a 130 nm CMOS process and its DC characteristic curve measurements show a 32 dB DC voltage gain at a 0.2 V supply voltage, and simulations show a 330 kHz and unity-gain-bandwidth product and 90 degrees phase margin for a 10 pF capacitive load, and a 450 nW power consumption also at a 200 mV supply voltage.
