US 5,331,581 A · Artificial random-number pattern generating circuit

Abstract

An artificial random-number pattern generating circuit has a plurality of flip-flops each having a set signal input terminal and a clock signal input terminal; a plurality of selectors each of which forwards its output to the corresponding flip-flop and receives a first operation mode signal and/or a second operation mode signal; and an exclusive logical OR gate. The artificial random-number pattern generating circuit functions in three different ways, that is, as an artificial random-number pattern generator, a boundary scanning buffer or an input buffer, in accordance with the combinations of the first and second operation mode signals. The circuit can make not only a diagnosis of failure in the internal circuit of the large-scale integration (LSI) but also overall tests including those for input and output buffer circuits of the mounted LSI chip on a board or those for external wirings for the LSI.

Claims8

Dependent claims

An N-bit artificial random-number pattern generator, comprising:

a plurality of N flip-flops, a first to N-th (N.gtoreq.2), each of which has an input terminal, a set signal input terminal and a clock signal input terminal;
a plurality of (N-1) selectors, a first to (N-1)th, each of which receives an output of said (1+i)th (1.ltoreq.i.ltoreq.(N-1)) flip-flop and an i-th input data and selectively forwards its output to said input terminal of said i-th flip-flop;
artificial random-number producing means for receiving outputs from at least two of said N flip-flops, conducting a predetermined logical operation on said outputs, and outputting an artificial random-number data of 1 bit;
and
an N-th selector which receives the output data from said artificial random-number producing means, an external output data, and an N-th input data, and which selectively forwards its output to the input terminal of said N-th flip-flop, said N-th selector being directly supplied with a first operation mode signal and a second operation mode signal.

2 more elements

An N-bit artificial random-number pattern generator, comprising:

a plurality of (N+1) flip-flops, a first to (N+1)th (N.gtoreq.2), each of which has an input terminal, a set signal input terminal and a clock signal input terminal;
a plurality of N selectors, a first to N-th, each of which receives an output of said (1+i)th (1.ltoreq.i.ltoreq.N) flip-flop and an i-th input data and selectively forwards its output to said input terminal of said i-th flip-flop;
artificial random-number producing means for receiving outputs from at least two of said (N+1) flip-flops, conducting a predetermined logical operation on said outputs, and outputting an artificial random-number data of 1 bit;
and
an (N+1)th selector which receives the output data from said artificial random-number producing means and an external output data, and which selectively forwards to the input terminal of said (N+1)th flip-flop one of said output data from said artificial random-number producing means and said external output data, said (N+1)th selector being directly supplied with a first operation mode signal and a second operation mode signal.

2 more elements

Dependencies are inferred from the claim text.

Artificial random-number pattern generating circuit

Life of this patent

Artificial random-number pattern generating circuit

Life of this patent

Abstract

Claims8