Douglas C Kay

US Patent:

56401140, Jun 17, 1997

Filed:

Dec 27, 1995

Appl. No.:

8/578101

Inventors:

Douglas Kay - Los Gatos CA

Assignee:

VLSI Technology, Inc. - San Jose CA

International Classification:

H03K 3289

US Classification:

327202

Abstract:

A scan flip-flop includes a data input, a scan input, a mode selection input, a mode control input and a clock input. When the mode selection input is set to a first selection value, and the mode control input is set to a first control value, the scan flip-flop operates as a D flip-flop. When the mode selection input is set to a second selection value, the scan flip-flop shifts in a scan input value on the scan input when one of the mode control input and the clock input is toggled. Also, as long as the mode selection input is set to the first selection value, and the mode control input is set to a second control value, the scan flip-flop holds a current value within the scan flip-flop.

US Patent:

59387823, Aug 17, 1999

Filed:

Sep 24, 1996

Appl. No.:

8/719149

Inventors:

Douglas Kay - Los Gatos CA

Assignee:

VLSI Technology, Inc. - San Jose CA

International Classification:

G01R 3128

US Classification:

714726

Abstract:

A scan data flip-flop having improved timing characteristics is provided. A scan flip-flop includes: a first data input coupled with a first latch; a second data input coupled with said first latch; a clock input coupled with said first latch; a data control input; and a data controller operably coupled with said clock input and said data control input and said first latch; said data controller being configured to generate an enable signal responsive to a clock signal from said clock input and a data control signal from said data control input, and said enable signal to control the input of data into said first latch. The normal or first data input signal is preferably directly applied to the first latch within the scan data flip-flop according to the present invention. The data controller of the scan data flip-flop according to the present invention is preferably void of a multiplexer. A method for controlling the entry of data into a scan data flip-flop is also provided.