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:
Oct. 26, 1999
Filed:
Mar. 31, 1998
Robert W Leiby, Ft. Collins, CO (US);
Hewlett Packard Company, Palo Alto, CA (US);
Abstract
An inverting amplifier having variable gain in M discrete steps that are a fixed ratio F apart may be constructed by grounding the non-inverting input of a high gain differential gain element, and connecting the inverting input through a single-pole M-throw switch to the N.sup.th terminal in a ladder network of M cascaded elements. Each element is a series R and X, with X grounded, and their junction being where the next element of the ladder is connected. These junctions are also the aforementioned terminals of the ladder network, and are what are coupled to the M throws of the switch. At an input end of the ladder network is another impedance Z, to which the input V.sub.in is applied. At the other end of the ladder network is a final R in series with another Z that is driven by the V.sub.out obtained from the output of the gain element. Once Z and F are selected R and X may be found according to the relationships R=Z[.sqroot.(1/F)-1]and X=Z[.sqroot.(1/F)]/[.sqroot.(1/F)-1]. FET's may used to provide a make before break switch. The setting of the switch picks N, which determines the variable gain.