Importance

Loading Importance Indicators...

Abstract

An apparatus for obtaining valid values during a built-in self-testing of logic ('LBIST') is disclosed. The apparatus includes a first multiplexer, a second multiplexer and a 1-hot init circuit. The 1-hot init circuit includes a scan register, a first inverter, a third multiplexer, a second inverter, and a fourth multiplexer. The scan register includes a plurality of state elements. The first multiplexer is coupled to receive a random data signal and an output of the 1-hot init circuit. Within the 1-hot init circuit, a next to last and a last state element of the scan register is coupled to the inverters and the third and fourth multiplexers, respectively. The first inverter is also coupled to the third multiplexer and the second inverter is coupled to the fourth multiplexer. The output of the fourth multiplexer is coupled to the input of the second multiplexer. Also coupled to the input of the second multiplexer is an input for the random data signal. The output for the second multiplexer is coupled to a signature compression circuit. Also disclosed is a method for flushing the state elements in the 1-hot init circuit for receiving a 1-hot value after flush. Also disclosed is a method for ensuring values that a 1-hot multiplexer selects are orthogonal and that inputs to a signature compression circuit are valid.

Loading the Abstract Image...

First Claim