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:
Jan. 27, 1976
Filed:
Mar. 08, 1971
Applicant:
Inventors:
Gary A Hart, Boulder, CO (US);
Melvin G Wilson, Rochester, MN (US);
Assignee:
International Business Machines Corporation, Armonk, NY (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H03F / ;
U.S. Cl.
CPC ...
330 10 ; 328145 ;
Abstract
Small current signals (0.5 ua and less) such as the output of a photodiode are direct current coupled to a preamplifier which also passes an impedance reducing injection current to a pair of amplifiers. A voltage output proportional to the logarithm of the signal current is produced by passing the amplified current through a log producing junction of a transistor. However, to produce the logarithm function accurately, the injected or impedance reducing current is precisionally removed so that only a very minute portion (one part out of 5000) passes through the log producing junction.