Pre-charge sample-and-hold circuit

Abstract

A precharge sample-and-hold circuit is formed by coupling a buffer with an input port and making use of a switch to conduct the circuit between the buffer and a total load capacitor for precharging according the state of a sample-and-hold circuit. When the sample-and-hold circuit is in the sample mode, it precharges the total load capacitor. When the sample-and-hold circuit is in the hold mode, the influence to the sampled signal is further reduced due to the precharging. The requirements of swing rate, output voltage swing, gain-bandwidth product for the opamps can therefore be reduced, hence being applicable to the realization of the design of advanced fabrication technologies of low supply voltages.