Abstract: An apparatus and method for protecting semiconductor switching devices from damage due to electrostatic discharge is provided. The apparatus detects the occurrence of an ESD event, and turns the switching circuit to an operating state in which electrostatic charge is dissipated through the switching circuit. In embodiments of the invention, the switching circuit is a CMOS inverter circuit and the apparatus includes a PMOS transistor that upon occurrence of an ESD event couples an output of the inverter circuit to ground to discharge the electrostatic charge.

Abstract: A diode-connected transistor device for IC protection against electrostatic discharge (ESD) that functions as a transistor in the active region during an ESD event. The device cell includes an annular collector at the outer reaches of the cell, a circular base diffusion concentric with the collector, and an annular emitter near the outer edge of the base. The base and emitter regions are connected together by metallization external to the transistor cell. With the base contact enclosed by the annular emitter, during an ESD spike the initial reverse bias current flow is from the collector, under the emitter diffusion and out of the base contact. Eventually, as the magnitude of the ESD spike increases, the reverse biased current becomes sufficient to locally forward bias the base-emitter junction changing the primary ESD current path from collector to base, to collector to emitter, thus lowering the ESD current density in the active base-collector junction.

Abstract: An electrostatic discharge (ESD) protection circuit formed on a semiconductor substrate includes a first stage clamping circuit and a second stage clamping circuit separated by a dissipative circuit. The first and second stage clamping circuits are designed to absorb and dissipate the high and low energy ESD, respectively. The first clamping circuit has a self-regulated current mechanism capable of diverting the electrical current generated by an ESD from a high current density region to a low current density region within the semiconductor substrate, and simultaneously lowers the ESD induced voltage for safe protection.

Abstract: A diode-connected transistor device for IC protection against electrostatic discharge (ESD) that functions as a transistor in the active region during an ESD event. The device cell includes an annular collector at the outer reaches of the cell, a circular base diffusion concentric with the collector, and an annular emitter near the outer edge of the base. The base and emitter regions are connected together by metallization external to the transistor cell. With the base contact enclosed by the annular emitter, during an ESD spike the initial reverse bias current flow is from the collector, under the emitter diffusion and out of the base contact. Eventually, as the magnitude of the ESD spike increases, the reverse biased current becomes sufficient to locally forward bias the base-emitter junction changing the primary ESD current path from collector to base, to collector to emitter, thus lowering the ESD current density in the active base-collector junction.

Abstract: Differentially-connected pairs of JFETs on an IC chip are protected from ESD events by connecting respective discharge control resistors to the drains of the JFETs in such a manner as to be in series with any flow of current through either JFET.

Abstract: An image sensing element in a solid state imaging device is provided with a plurality of superposed channels disposed at respective distances from a light receiving surface of the device, each of such channels having a different characteristic spectral response due to the differential absorption of light by a semiconductor. By so disposing the channels, the device becomes a color imaging sensor having optimized resolution. The top channel, i.e. the channel nearest the surface of the device, may be either a "surface" channel or a "buried" channel, the lower channel(s) being buried channels. Depending upon the design of the element, either electrons or holes may be accumulated as photocharges in respective superposed channels.