| 摘要 |
The present invention, enables complementing the state of either the master (L1) or slave latch (L2) in the shift register latches (SRLs) without changing the state of the other. When this is done after properly loading the LSSD scan chain using a normal scan chain sequence, the next system clock sequence can be used to launch a desired transition from each SRL in the scan chain. The actual mechanism for complementing the state of latches in LSSD scan chains can vary depending on which one of the L1 or L2 latch is being complemented; details of the actual scan chain and Shift Register Latch (SRL) design; and the semiconductor chip circuit technology. The complementing function can be provided as an integral part of the SRL design with minimal impact to system path and performance. An alternate complementing method would be to use a self complementing latch function. In this design, the latch to be complemented does not require an additional input containing the complement value, but rather uses its current state as reference and switches to the opposite state. To accomplish this, a complement signal similar to a latch reset (i.e., reset-to-complement) can be used.
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