Hybrid scan chains with flip-flops and latches

Abstract

An electronic circuit features a hybrid scan chain design comprising a flip-flop-based part of the scan chain and a latch-based part of the scan chain. The latch-based part may be included in an array of memory cells and includes one or more chain segments of storage memory cells. Chain segments are separated by chain buffer memory cells. Memory cells of each chain segment are coupled with a sequence generator that generates a sequence of non-overlapping pulses from a pulse in a scan clock (SCLK) signal. The circuit includes a memory element interfacing the scan out (SO) output of the flip-flop-based scan chain with the scan in (SI) input of the latch-based scan chain. The memory element captures and retains the value of the final flip-flop in the flip-flop-based scan chain, enabling subsequent access by the initial latch in the latch-based scan chain without loss of data.