PARTIAL SCAN CELL

摘要

An integrated circuit 2 is provided with a serial scan chain. Disposed between at least some serial scan cells 32, 34 forming a serial scan chain there is provided a partial scan cells 36. These partial scan cells are arranged such that during a scan mode in which serial data is being shifted into and out of the serial scan cells, a fixed value is captured and stored into the partial scan cell 36. This avoids the presence of unknown data values within the signal paths between the functional logic 38, 40 which is to be tested.

主权项

1. An integrated circuit comprising:
a serial scan chain comprising a plurality of serial scan cells, each of said plurality serial scan cells configured to operate under control of a clock signal:
(i) in a functional mode to capture and to store a functional signal value; and(ii) in a scan mode to serially shift scan signal values through said serial scan chain; and a partial scan cell connected in a signal path between a signal output of one serial scan cell of said serial scan chain and a signal input of another serial scan cell of said serial scan chain, said partial scan cell configured to operate under control of said clock signal:
(i) in said functional mode to capture and to store a signal value dependent upon a signal output from said one serial scan cell; and(ii) in said scan mode to capture and to store a fixed signal value.