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:
Jul. 06, 2010
Filed:
Dec. 20, 2007
Thirumalai Rengachari, Austin, TX (US);
Kartik Nanda, Dallas, TX (US);
Larry L. Harris, Austin, TX (US);
John Paulos, Austin, TX (US);
Thirumalai Rengachari, Austin, TX (US);
Kartik Nanda, Dallas, TX (US);
Larry L. Harris, Austin, TX (US);
John Paulos, Austin, TX (US);
Cirrus Logic, Inc., Austin, TX (US);
Abstract
A temperature and process-stable magnetic field sensor bias current source provides improved performance in Hall effect sensor circuits. A switched-capacitor sensing element is used to sense either a reference current or the bias current directly. A current mirror may be used to generate the bias current from the reference current, and may include multiple current source transistors coupled through corresponding control transistors that are switched using a barrel shifter to reduce variations in the bias current due to process variation. The current mirror control may be provided via a chopper amplifier to reduce flicker noise and the current mirror control voltage may be held using a track/hold circuit during transitions of the chopper amplifier to further reduce noise due to the chopping action.