Design and operation of a floating gate amplifier

A unique amplifier configuration is examined that fully exploits the intrinsically high signal-to-noise performance of charge-coupled devices (CCD´s). In this amplifier, the signal charge is detected with a conducting `floating gate´ embedded in the oxide between a bias electrode and the silicon substrate. The change of voltage on the floating gate produced by the signal charge in the CCD channel is then used to modulate the current flow in a metal-oxide-semiconductor (MOS) transistor. The signal charge remains isolated and can be moved downstream in the CCD channel; thus, it can be detected again by other similar structures. Computer analysis, test structure design, and experimental results of a floating gate amplifier (FGA) are presented.