US 4,733,405 A · Digital integrated circuit

Abstract

A digital integrated circuit incorporates a plurality of multi-port flip-flop circuits which are interconnected by a plurality of gate circuits. A separate source of clock pulses is provided for each of the ports of the multi-port flip-flop circuits, and each clock pulse source is selectively effective to cause the multi-port flip-flop circuits to perform independent functions. During operation under one source of clock pulses, the flip-flops perform their ordinary function as D type flip-flops. During operation under another source of clock pulses, the flip-flops function as one or more shift registers in order to set the flip-flops to a predefined initial state in accordance with serial input data, and/or to provide serial output data in response to the state of the flip-flops following a preceding operation. When a further source of clock pulses is effective, a plurality of flip-flops may be connected to function as a random number generator or as a signature generator so as to perform repetitive operations such as cycling the address inputs of a ROM and providing output signals corresponding to the operation of the ROM.

Claims16

Dependent claims

In a digital integrated circuit having a plurality of clock flip-flop circuits and including first and second sources of clock signals, one of said sources being active at a time, each of said flip-flop circuits being a multiport flip-flop circuit and comprising, in combination:

first and second gate input terminals for receiving first and second gate, respectively,
first and second gate transistors connected to said first and second gate input terminals, respectively,
said first and second gate transistors being controlled by said first and second clock signals, respectively,
a first inverting circuit connected to said first and second gate transistors, and
third and fouth gate transistors serially connected to said first inverted circuit and controlled by said first and second clock signals, respectively;
whereby said integrated circuit including said multiport flip-flop circuits can perform plural functions independently with the application of one of said first and second clock signals to said first and third gates or to said second and fourth gates of said multiport flip-flop circuits.

3 more elements

A method of testing an integrated circuit made up of a plurality of interconnected clock flip-flop circuits and first and second sources of clock signals, one of said sources being active at a time, comprising the steps of:

interconnecting said flip-flop circuits for normal operation to perform the functions of said digital integrated circuits when one of said first and second sources of clock pulse signals is applied thereto,
arranging the connections of said plurality of said flip-flop circuits to constitute at least one shift register not employed in the normal operation of said digital integrated circuit whereby an arbitrary series of data bits may be shifted into said shift register in synchronism with the other of said first and second sources of clock pulses, whereby said plurality of flip-flops can be preset to a state corresponding to said arbitrary input data,
and subsequently applying signals of the first of said first and second sources of clock signals for resuming normal operation of said digital and inverted circuit from the state corresponding to said arbitrary sequence of input data bits.

Dependencies are inferred from the claim text.

Digital integrated circuit

Life of this patent

Digital integrated circuit

Life of this patent

Abstract

Claims16