BALLAST: a methodology for partial scan design

In the proposed partial scan methodology, the scan path is constructed so that the rest of the circuit belongs to a class of circuits called balanced sequential structures. Test patterns for this structure are generated by treating it as being combinational. Each test pattern is applied to the circuit by shifting it into the scan path. holding it constant for a fixed number of clock cycles, loading the test result into the scan path, and then shifting it out. This technique achieves full coverage of all detectable faults with a minimal number of scannable storage elements and using only combinational test pattern generation.<>