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Binary Counter Testing Sequence Generator

IP.com Disclosure Number: IPCOM000078450D
Original Publication Date: 1973-Jan-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Hong, SJ: AUTHOR [+4]

Abstract

Fig. 1 shows the block diagram of the overall testing system. Assuming that the total number of known test patterns is n, then the test patterns are denoted by Z(1), Z(2), ... Z(n). Each test pattern is a k-digit binary input to the chip under test. Thus, k binary time sequences, called test sequences, are generated simultaneously. Each test sequence is n digits long. Let T(1), T(2), ... T(k) denote these test sequences. Typical values of n and k are n < 1000, k < 100; however, the scheme is applicable to any values. The test sequence generator is a hardwired combinational network with a binary counter as the sequence source.

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Binary Counter Testing Sequence Generator

Fig. 1 shows the block diagram of the overall testing system. Assuming that the total number of known test patterns is n, then the test patterns are denoted by Z(1), Z(2), ... Z(n). Each test pattern is a k-digit binary input to the chip under test. Thus, k binary time sequences, called test sequences, are generated simultaneously. Each test sequence is n digits long. Let T(1), T(2), ... T(k) denote these test sequences. Typical values of n and k are n < 1000, k < 100; however, the scheme is applicable to any values. The test sequence generator is a hardwired combinational network with a binary counter as the sequence source.

Consider the r x 2/r/ matrix G in which the j/th/ column (j=0, 1,..., 2/r/-1) is a r- digit binary number j. The matrix G for r=4 is illustrated below:

(Image Omitted)

The rows of G are denoted by g(1), g(2), ... g(r), respectively. These sequences (set G) can be generated simultaneously using a r-stage binary counter. These rows are then fed through a combinational network to generate any binary sequence T of length 2/r/ or less. For example,

(Image Omitted)

The Boolean network of Fig. 2 will generate the sequence T with the sequence set G as its input.

For sequences of length 1000, a 10-stage counter is needed for generation. Any number of sequences T(1), T(2), ... T(k) of length 1024 or less, can be generated from the 10 counter sequences g(1), g(2), g(3),...g(10) using a combinational Boolean net...