All digital transistor high gain operational amplifier using positive feedback technique

New all digital-transistor CMOS very high DC-gain amplifiers that use internal positive-feedback technique are presented. These structures don't require perfect matching of transistors to achieve the very high DC gain, and have a very low gain sensitivity to output swing. An implementation of a sample and hold circuit constructed using one of the proposed amplifiers is described. Special layout pattern is used to cut the parasitic capacitance.