Circuit for boosting encoding capabilities of test stimulus decompressors

摘要

The circuit for boosting encoding capabilities of test stimulus decompressors is utilized in conjunction with a stimulus decompressor. The circuit, called align-encode is inserted between the decompressor and internal. The scan chains feed into a response compactor. The align-encode circuit is used to judiciously manipulate care bit distribution. Re-configurability of the align-encode circuit allows for this manipulation via delay cells with the align-encode circuit, whose length can be adjusted on a per scan chain per test pattern basis by loading the align-encode circuit with proper control data. Based on the stimulus decompressor characteristics, the scan chains are delayed in such a way that an unencodable pattern becomes encodable when using the align-encode circuit.