A static RAM memory is ideally suited for BiCMOS processes. As in standard CMOS memory cells, the cells have cross-coupled inverters that have more efficient n-channel transistors for the drive transistors, which pull a bit line low during a read operation. The weaker p-channel transistors are used for load transistors in the cross-coupled inverters, adding to cell stability while requiring no power. In contrast to prior-art cells, p-channel pass transistors are used. Common-emitter word-line drivers are also used that require a small input-voltage swing in comparison with the large word-line voltage swing. A low voltage on the word line selects a memory cell by causing p-channel pass transistors to conduct, coupling bit lines to the cross-coupled inverters in the memory cell. Power consumption is reduced since only one selected word line is at a low voltage, while the deselected word lines are at a high voltage. Common-emitter word-line drivers have a conduction path from the positive supply terminal to ground when the output word line is low, but no conduction path when the output word line is high. Thus only the common-emitter word-line driver that is connected to the selected low word line consumes appreciable power.

A regenerative comparator with a differential amplifier pair of transistors (Q.sub.1D, Q.sub.1E, Q.sub.2D, and Q.sub.2E) and a differential regenerative pair of transistors (Q.sub.3D, Q.sub.3E, Q.sub.4D, and Q.sub.4E), utilizes one or more of the following three techniques to reduce hysteresis by reducing the amount of charge storage in transistors. First, the transistors are arranged in a bootstrap cascode configuration having a depletion mode device (Q.sub.D) and an enhancement mode device (Q.sub.E). Second, a differential amplifier pair source-coupling implementation (D.sub.1 -D.sub.4, Q.sub.5A -Q.sub.5C, and Q.sub.6A -Q.sub.6C) allows current to flow through the transistors of the differential amplifier pair and differential regenerative pair independent of whether current is flowing through the branch (52 or 4) that connects the emitters or sources of the enhancement devices of the amplifier pair and regenerative pair. Third, the comparator includes keep-alive current sources (Q.sub.KA1 -Q.sub.KA4) that allow current to flow through the amplifier pair and regenerative pair independent of the magnitude of the difference in gate input voltages being compared.

The invention is a radiation hardened bistable logic circuit employing two pairs of parallelly connected transistors, cross coupled through diode "OR" circuits, with back-to-back diodes between the gates or bases of the two FETs or bipolar transistors comprising each pair.

A static random access memory wherein all cells have p-channel access transistors, p-channel driver transistors, and n-channel loads. The access transistors have a width to length ratio which is greater than the width to length ratio of the driver transistors. The bit lines are precharged close to VSS, and the wordlines are held near VCC in the off state. Thus the operating signals in the array of the SRAM of the present invention are opposite to those in SRAMs of the prior art.

A latch includes a pair of inverters cross-coupled between a storage node and a feedback node. A capacitor is conditionally coupled to the feedback node through a pass gate such that the capacitor is coupled to the feedback node when the latch holds data and is not coupled to the feedback node when the latch is loading. The capacitor reduces the latch's susceptibility to soft errors when holding data, and does not appreciably slow the latch when data is loading. The capacitor is implemented using the gate capacitance of complementary transistors. A flip-flop includes cascaded latches, one or more of which have a switched capacitor on a feedback node.