Used for testing general digital logic, control units, and CPU cores.
An incorrect logical signal value (e.g., a 0 instead of a 1 ) caused by a fault during system operation. The Limits of Functional Testing
The wire behaves as if it is permanently tied to the power rail ( VDDcap V sub cap D cap D end-sub digital systems testing and testable design solution
The you are working with (e.g., FPGA, custom ASIC, or embedded memory).
The multiplexer routes functional data through the chip, allowing it to act like a normal circuit. Used for testing general digital logic, control units,
LBIST targets standard combinational and sequential random logic structures.
Uses a Linear Feedback Shift Register (LFSR) to generate pseudo-random test patterns and a Multiple-Input Signature Register (MISR) to compress the outputs into a unique digital "signature." If the signature matches the golden standard, the chip passes. The multiplexer routes functional data through the chip,
By shifting data into the scan chains, an external tester can establish any arbitrary internal state (Controllability). After applying a single functional clock cycle to capture the system's response, the new internal states can be shifted out and verified (Observability). Built-In Self-Test (BIST)
If you are developing a specific hardware architecture, we can explore how to implement these strategies for your design. Let me know:
Standard flip-flops are replaced with "Scan Flip-Flops" that feature an internal multiplexer (MUX).
The multiplexers link all internal flip-flops together in a long serial chain (a scan chain). Test patterns are shifted serially into the chip, the circuit executes for one clock cycle in normal mode, and the resulting captured states are shifted serially out to an external tester.