Signature encoding for integrated circuits
First Claim
1. In an integrated circuit chip having circuit means for performing a logic function and a plurality of input/output terminals upon which the logic levels associated with said function appear, the improvement comprising:
- additional circuit means formed within said chip and being independent of said circuit means for performing said logic function, said additional circuit means being coupled to predetermined ones of said input/output terminals for encoding a fixed unalterable digital reference pattern within said chip.
2 Assignments
0 Petitions
Accused Products
Abstract
The present disclosure describes an improved integrated circuit chip which includes in addition to the logic circuits for performing its design function, an additional circuit for providing a unique reference pattern in digital form useful for test purposes. This reference pattern is automatically read by the tester and gives information as to the type of chip and its final signature. The former indicates to the tester an appropriate test routine such as a pseudo-random binary sequence; and the latter, the predetermined digital pattern which will be present on all of the input and output terminals of a properly functioning integrated circuit chip at the conclusion of the test. Since each chip signature is read by the tester itself, no reference to signatures customarily recorded in tables or inscribed on circuit schematics is required by the test technician.
53 Citations
12 Claims
-
1. In an integrated circuit chip having circuit means for performing a logic function and a plurality of input/output terminals upon which the logic levels associated with said function appear, the improvement comprising:
additional circuit means formed within said chip and being independent of said circuit means for performing said logic function, said additional circuit means being coupled to predetermined ones of said input/output terminals for encoding a fixed unalterable digital reference pattern within said chip. - View Dependent Claims (2, 3, 4)
-
5. In a test system including an integrated circuit chip having circuit means for performing a logic function, said chip comprising:
-
a plurality of input/output pins associated with said logic function and at least one additional test pin, additional circuit means formed within said chip for encoding a predetermined fixed digital reference pattern therein, said additional circuit means being independent of said circuit means for performing said logic function, said additional circuit means comprising a plurality of unidirectional current conducting devices, each device having at least first and second electrodes, the first electrodes of said devices being connected respectively to selected ones of said input/output pins in accordance with said predetermined reference pattern, the second electrodes of said devices being connected to a common bus, said bus being connected to said test pin, the connection of a unidirectional current conducting device to a given one of said selected pins being indicative of a first binary state associated with said given pin and the absence of said device at another non-selected pin being indicative of a second binary state associated therewith, the respective binary states present on said input/output pins and the signal levels corresponding respectively thereto defining said predetermined fixed digital reference pattern. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
-
Specification