Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
Disclosed is a linear feedback shift register (LFSR) circuit that can act as either a parallel pseudorandom pattern generator (PRPG) or as a multiple input signature register (MISR). Consider the PRPG shown in Fig. 1. (Image Omitted)
Disclosed is a linear feedback shift register (LFSR) circuit that can act as either a parallel pseudorandom pattern generator (PRPG) or as a multiple input signature register (MISR). Consider the PRPG shown in Fig. 1.
An interesting property of the PRPG implementation shown in Fig. 1 is that it contains the same number of 2-way Exclusive-ORs as a MISR constructed from the same characteristic polynomial. This MISR is shown in Fig. 2. This similarity has value in developing a cell or macro block in an integrated circuit layout.
A macro cell, which would be personalized with wiring patterns as either a response compressor (MISR) (Fig. 3a) or as a stimulus generator (PRPG) (Fig. 3b), is shown. In the MISR case, the output of the shift register latch (SRL) is fed into the Exclusive-OR along with the response to be compressed. The output of the Exclusive-OR is then fed to the input of the next SRL. The PRPG connection has the output of the SRL feeding both the Exclusive-OR and the input of the next SRL. The other input to the Exclusive-OR is the x0 bus and the output of the Exclusive-OR is the channel output.
The other PRPG/MISR application requires logic be added to switch the function of the circuit from one mode to the other. This application, shown in Fig. 4, is somewhat like the BILBO [*] circuit, except that a much improved PRPG is formed. This circuit is useful in built-in test applications. In the reconfigurable PRPG/MISR (RPM?...