Patent ID: 8723556

Claim:
A sampling circuit that operates in at least a sample state and a hold state comprising: an input terminal receiving a time variable input signal; a semiconductor switch that operates in at least a non-conductive mode and a conductive mode as directed by an amount of charge applied to a control terminal, the semiconductor switch being coupled between the input terminal and an output terminal, the semiconductor switch body being accessible at a body bias terminal; a body bias circuit coupled between the body bias terminal and the input terminal that maintains, in sample and hold states, respectively, a predetermined and substantially constant body bias voltage difference between these terminals; a charge generator that is non-coupled to the input signal and coupled to the control terminal; and a control circuit coupled to the charge generator and the body bias circuit to control the body bias circuit, wherein the control circuit selectively directs the charge generator to deliver a predetermined amount of charge to the control terminal such that the impedance of the semiconductor switch during a sample state is maintained substantially constant.