Synopsys, Inc.

Timothy N Ayres

Ajay Khoche

Amitava Majumdar

Peter Wohl

John A Waicukauski

Michio Komoda

A method to perform launch-on-shift scanning for integrated circuits having multiple clock domains is presented. An integrated circuit includes both capture clock domains and non-capture clock domains. The portions of the test vectors for non-capture clock domains are shifted into the scan chains of the non-capture clock domains and allowed to settle prior to the last shift launch cycle and the capture cycle of the capture clock domains. Thus, the ambiguity of the timing between the non-capture domains and the capture domains caused by asynchronous clock signals is eliminated.

Launch-on-shift support for on-chip-clocking

In a multiport memory semiconductor integrated circuit, an efficient method of testing the memory for faults. The method determines a base address in a multiport memory. A plurality of addresses are scanned within the memory which are at a hamming distance of 1 from the base address, such that at least two memory cells in each column of the multiport memory device are accessed in the scan. This allows the detection of cross port faults, address mismatch faults, and bit shorts due to the fact that the faults are exposed when the two memory cells sharing access columns are accessed with test data. The method functions nominally without requiring any detailed information about the placement and routing structure of the multiport memory device.

Built in self test algorithm that efficiently detects address related faults of a multiport memory without detailed placement and routing information

A circuit for efficiently performing shadow logic testing and memory block testing within a semiconductor integrated circuit. The integrated circuit includes a memory block for storing data. A shadow logic circuit is coupled to the memory block for interfacing the memory block with external circuitry. The shadow logic provides inputs to the memory block and receives data outputs from the memory block. A test collar is coupled between the memory block and the shadow logic. The test collar receives the data inputs from the shadow logic and receives the data outputs from the memory block. The test collar is configured to both provide test inputs to the shadow logic and capture test outputs from the shadow logic independent of the memory block. The test collar is also adapted to both provide tests inputs to the memory block and capture test outputs from the memory block independent of the shadow logic. Thus, the built in test circuit of the present invention is able to perform precise isolated testing on the memory block and perform precise isolated testing on the shadow logic.

Circuit for efficiently testing memory and shadow logic of a semiconductor integrated circuit

Circuit for efficiently testing memory and shadow logic of a

The method of controlling ground bounce during DC parametric tests disclosed herein is based on the formulation of tests that best achieve two broad goals. The first goal is to reduce the number of I/O pins that are switched simultaneously. In the formulation of the VIL and VIH tests this goal is implemented by preferably only switching one input at a time. The second goal is to simultaneously switch I/O pins that are distant from one another. In the formulation of the VOL and VOH tests this goal is implemented by partitioning the outputs into subsets and selecting preferably one and only one output at a time from each and every subset.

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Milpitas, CA, United States of America

Timothy N Ayres