A sampling circuit can include a switch having a control terminal, a first channel terminal and a second channel terminal. The first channel terminal can be configured to receive an input signal, and the control terminal can be configured to have a control voltage that varies with regard to the input signal, such that a conducting channel can be formed between the first channel terminal and the second channel terminal to enable an output voltage on the second channel terminal to track the input signal. Further, the sampling circuit can include a bootstrap module coupled to the control terminal of the switch. The bootstrap module can be configured to change the control voltage by a substantially constant value to turn off the conducting channel between the first channel terminal and the second channel terminal in order to hold the output voltage as a sample of the input signal.