Method for generating test patterns to detect an electric shortcircuit, a method for testing electric circuitry while using test patterns so generated, and a tester device for testing electric circuitry with such test patterns

A method for testing electric circuitry to detect electric shorts between respective separate nets therein such that a minimum number of test vectors is required, said method comprising the steps of:

• determining the number N of nets to be tested;
• defining a two-dimensional array of bits having P rows and N columns, wherein (i) N is the number of nets to be tested, (ii) a single row forms a test vector, (iii) P is the number of test vectors wherein each test vector includes N bits which are applied simultaneously to the different nets, and (iv) a single column forms a test sequence and includes P bits to be applied successively to a particular net;
• choosing a predetermined minimum Hamming distance between the test sequences of respective nets;
• determining the minimum number of test vectors required to detect the electric shorts between the nets in the electrical circuitry;
• generating the test sequences in accordance with the predetermined minimum Hamming distance and the minimum number of test vectors;
• and
• applying the test vectors to the electrical circuitry.

A tester device for testing electric circuitry with test vectors to detect electric shorts between respective separate nets in the electrical circuitry such that a minimum number of test vectors is required, said device comprising:

• array means for defining a two-dimensional array of bits having P rows and N columns, wherein (i) N is the number of nets to be tested, (ii) a single column of the N columns forms a test sequence and includes P bits which P bits are to be applied successively to a particular net, (iii) P is the number of test vectors, and (iv) a single row of the P rows forms a test vector and includes N bits which N bits are to be applied simultaneously to the different nets;
• means for generating the N columns in accordance with (a) a predetermined Hamming distance and (b) the minimum number of test vectors required to find the electric shorts between the nets of the electric circuitry;
• and
• means for applying the test vectors to the electrical circuitry.

A method for generating test vectors to detect electric shorts between respective separate nets in electric circuitry such that a minimum number of test vectors is required, said method comprising the steps of:

• determining the number N of nets to be tested;
• choosing a bit error detectable code having a word length of P, whereby P is at most equal to P=log.sub.2 (N+2)+2, and an associated minimum Hamming distance;
• defining a two-dimensional array of bits having P rows and N columns, wherein (i) N is the number of nets to be tested, (ii) a single row forms a test vector, (iii) P is the number of test vectors wherein each test vector includes N bits which are applied simultaneously to the different nets, and (iv) a single column forms a test sequence and includes P bits to be applied successively to a particular net;
• selecting N code words in said code to fill said array;
• and
• applying the test vectors to the electric circuitry.