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.

Date of Patent:
Oct. 12, 2010

Filed:

Aug. 28, 2008
Applicants:

James Borthwick, Sunnyvale, CA (US);

Peter P. Cuevas, Los Gatos, CA (US);

Tal Raichman, San Francisco, CA (US);

Inventors:

James Borthwick, Sunnyvale, CA (US);

Peter P. Cuevas, Los Gatos, CA (US);

Tal Raichman, San Francisco, CA (US);

Assignee:

QualiTau, Inc., Sunnyvale, CA (US);

Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G05F 3/02 (2006.01); G01R 31/26 (2006.01);
U.S. Cl.
CPC ...
Abstract

A current source is provided with two resistor banks, and digital potentiometers are used to control how much each resistor bank affects the resulting output current. Furthermore, when the digital potentiometers are at a particular setting such that a particular resistor bank does not affect the resulting output current (i.e., the resistor bank is 'inactive'), the resistance of that resistor bank can be switched without affecting the output current, thus minimizing or eliminating discontinuities in the output current during a current sweep operation. Thus, for example, when a resistor bank meets its threshold and becomes inactive, the resistance of the inactive resistor bank may be switched, and then the digital potentiometer setting may be changed to facilitate smoothly reactivating that resistor bank, with the new resistance.


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