Reconfigurable low voltage inverter-based sample-and-hold amplifier

In this paper, a voltage-scalable inverter-based operational amplifier suitable to be used in a reconfigurable ADC is optimized. A very low voltage sample-and-hold (SHA) circuit based on this opamp is presented to test the feasibility of a reconfigurable pipeline ADC. Simulations using STMicroelectronics 45-nm device models show that the opamp gain remains quite constant up to a supply voltage of 0.5V, and the amplifier can still be used with a supply as low as 0.3V. The SHA maximum sampling frequency decreases with supply voltage, and good performance with low power consumption is achieved.