Abstract: The gate insulator of an IGFET, whose gate is connected to the input terminal of a circuit, is protected by limiting the potential difference between any two circuit terminals. Each input and output terminal of the circuit is connected via protective diodes to the power supply lines of the circuit and a high conductivity, low reverse dynamic impedance, diode is connected between the power supply lines. The reverse voltage across the high conductivity diode is less than that of any other diodes at a given current level, whereby only the high conductivity diode conducts substantial currents in the reverse direction.

Abstract: Low resistance substrate contacts extending through the source region of an insulated gate field effect transistor (IGFET) will reduce parasitic bipolar effects in an integrated circuit. Such low resistance contacts may be made by diffusing impurities of a type opposite to the conductivity type of the source region through spaced areas of the source region thereby to provide low resistance paths between all points in the source and the underlying substrate. The low resistance contacts prevent large voltage drops in the substrate underlying the source thereby preventing "latch-up" of the parasitic devices formed during the manufacture of the integrated circuit.

Abstract: In the "on" condition of the circuit, a current mirror supplies a constant current to a comparator, a voltage divider circuit supplies a reference voltage to one input terminal of the comparator, and the input voltage to be compared to the reference voltage is applied to the other input terminal of the comparator. In the "off" condition of the circuit, the current mirror, the comparator and the voltage divider circuit are all cut off to reduce to substantially zero the power consumption of the circuit.