A track and hold circuit is disclosed, including: a source follower coupled to a voltage supply; a MOS transistor with well structure, the MOS transistor having a gate terminal coupled to a gate terminal of the source follower, a drain terminal coupled to its body terminal and a source terminal of the source follower, and a source terminal coupled to a current source and an output terminal; a capacitive device having a terminal coupled to the gate terminal of the MOS transistor and another terminal coupled to a fixed voltage level; and a switch device coupled and disposed between an input signal and the gate terminal of the MOS transistor, wherein the switch device is controlled by a control signal.