Patent ID: 8006150
Filing Date: 2011-08-23
Classification: G01R

Abstract:
1. A circuit for increasing scan cell observability of a response compactor, comprising: an x-align circuit inserted between the response compactor and a plurality of internal scan chains, the scan chains feeding into the x-align circuit, with additional inputs to the x-align circuit being control data, the x-align circuit being configured by the control data for receiving response data from the internal scan chains and manipulating the response data prior to sending the manipulated response data to the response compactor, wherein said x-align circuit includes a plurality of multiplexers, each of the scan chains having a corresponding one of the multiplexers connected thereto, and a plurality of delay registers, at least one of the delay registers being connected in scan-out paths of each of the scan chains between the scan chain and the scan chain's corresponding multiplexer, each of the delay registers delaying the corresponding scan chain for one cycle when enabled by the control data; and at least one control register connected to each of the multiplexers, respectively, for determining how many delay registers are inserted on the corresponding scan-out path.