The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 30, 1978
Filed:
May. 06, 1977
Applicant:
Inventors:
Thomas M Frederiksen, San Jose, CA (US);
Robert S Sleeth, San Jose, CA (US);
William M Howard, Campbell, CA (US);
Assignee:
National Semiconductor Corporation, Santa Clara, CA (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H03F / ; G03B / ;
U.S. Cl.
CPC ...
330261 ; 2502 / ; 330 59 ; 330257 ; 330260 ; 354 / ;
Abstract
A differential amplifier has one input connected to a reference potential and a photo diode connected in series with a level shift to the other input. A negative feedback loop is also coupled into other input. This stabilizes the amplifier and, if the level shift is made equal to the reference potential, biases the photo diode to zero, thereby reducing leakage current. A second feedback loop is used to adaptively bias the tail current in the differential amplifier.