Granted Patent
Utility
US 4,990,868 · App. 07/405,089
Modified progressive impedance ladder network
Inventor:
Dan Barbour
Patented Case
View Patent ↗
Granted: Feb 5, 1991
Filed: Sep 6, 1989
Inventor
Dan Barbour
Assignee (at issue)
Rockwell International Corporation
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.