Abstract: An improved fast track and hold amplifier having a hold capacitor in which in one embodiment a diode switching bridge is connected in a feedback loop of a transimpedance amplifier and in which in another embodiment a feedback resistor is connected in the feedback loop of a transimpedance amplifier is disclosed. The transimpedance amplifier provides a current signal representative of the current necessary to drive the voltage on the hold capacitor to the level of the input analog signal, and current mirrors connected to the hold capacitor respond to the current signal to charge up the hold capacitor to the level of the input signal by supplying a charging current to the hold capacitor that is a multiple of the current necessary. Devices constructed in accordance with the invention exhibit slew rates, droop rates and bandwidths comparable to or better than those of the heretofore known devices but at substantially lower power levels than heretofore possible.