US 4,794,570 AGranted

Self-timed programmable logic array with pre-charge circuit

AssigneeDigital Equipment Corporation

InventorsRobert C. Rose, Jash Patel

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Abstract

A programmable logic array includes a decoder section and an encoder section connected by a plurality of minterm conductors. The decoder section receives a plurality of input signals and in response selects appropriate ones of the minterm conductors. The selection of the minterm conductors enable the encoder selection to transmit a plurality of output signal on respective output conductors. The decoder and encoder sections include a plurality of stages, each controlling a minterm conductor and output conductor in response to the input signals and the selection of the minterm conductor. The stages include control transistors that are connected between a node, to which the respective minterm and output conductors are connected, and switches which enable and disable the control transistors. The nodes are initially precharged while the switches disable the respective transistors. After precharge, the switches enable the transistors in the decoder and encoder section respectively. A self timing circuit controls the switches to ensure that the switches are correctly timed.

Claims1

Dependent claims

A programmable logic array comprising an input decoder section and an output encoder section connected by a plurality of minterm conductors, said input decoder selecting a minterm conductor in response to the encoding of a plurality of input signals, and the output encoder section transmitting a plurality of output signals each on a respective output bit line and having an encoding determined by the selected minterm conductor,

A. said input decoder section including a plurality of decoder stages each connected to a node to which one of said minterm conductors is connected, at least some of said decoder stages including at least one control transistor connected to said respective node for controlling the selection of said minterm conductors under control of an input signal,
B. said output encoder section including a plurality of stages each connected to a node to which one of said output conductors is connected, at least some of said stages including at least one control transistor connected to said respective node for controlling the transmission of an output signal on said output conductor in response to the selection of said minterm conductor, said programmable logic array further including precharge means for precharging the respective nodes, each of said control transistors being connected between said respective nodes and a switch means and having a control terminal controlled in response to said respective input signal or the selection of said respective minterm conductors, said switch means being responsive to enabling signal for selectively enabling said control transistors.

Dependencies are inferred from the claim text.