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:
Nov. 27, 2007
Filed:
Dec. 28, 2005
David Dearn, Malmesbury, GB;
Holger Haiplik, Swindon, GB;
David Dearn, Malmesbury, GB;
Holger Haiplik, Swindon, GB;
Wolfson Microelectronics plc, Edinburgh, GB;
Abstract
A current sensing circuit for sensing the current through a main switch, such as the PMOS or NMOS switches of a switching regulator, is disclosed. The circuit includes a mirror switch, said mirror switch being substantially similar to said main switch but with a smaller aspect ratio, a difference amplifier for ensuring that the voltage across said first leg and across said second leg are substantially equal and thereby to derive from said mirror switch a sensing current nominally equal to a current flowing in said main switch divided by a sensing ratio, a current source for producing a quiescent current in said difference amplifier and a compensatory device for compensating for said quiescent current such that said current sensing circuit can sense currents in the main switch which are smaller than the quiescent current multiplied by the sensing ratio. The compensatory device may be one or two switches essentially similar to the mirror switch.