Abstract: A current source is switchable between two precisely defined output currents. A terminal of a coupling capacitor is coupled to the gate of an output MOSFET. The other terminal of the capacitor is switched between two reference voltages to toggle the output MOSFET to output the selected one of the two currents. A switchable bias voltage source is coupled to the gate only during the on state of the output MOSFET to set the gate voltage of the output MOSFET. The current output of the current source is quickly and accurately changed. A reference MOSFET is not directly coupled to the output MOSFET, so there are no slow settling components coupled to the gate of the output MOSFET.

Abstract: Circuits and methods that improve the performance of electronic sampling systems are provided. Parasitic capacitance associated with bootstrap circuitry is reduced, thereby decreasing signal distortion caused by capacitive loading at the input of the sampling circuit. The impedance of a sampling semiconductor switch is maintained substantially constant during sample states, at least in part, by accounting for non-linear parasitic capacitances associated with a sampling switch control terminal in order to reduce or minimize signal distortion associated with sampled signals that pass through the sampling switch.