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. 28, 1998
Filed:
Sep. 18, 1996
Douglas L Smith, Tucson, AZ (US);
Burr-Brown Corporation, Tucson, AZ (US);
Abstract
A compensated bias current circuit for use in an operational amplifier including a differential input stage, a gain stage, and an output driver stage. The compensated bias current circuit includes a PNP current mirror control transistor having an emitter coupled to a first supply voltage conductor, a collector coupled by a first conductor to a first terminal of a current source circuit, and a base connected to a second conductor, with the second conductor connected to first and second PNP current mirror output transistors in the gain stage and a third PNP current mirror output transistor in the output driver stage. The compensated bias current circuit also includes an NPN current mirror control transistor having an emitter coupled to a second supply voltage conductor and a collector and base coupled by a third conductor to a second terminal of the current source circuit, a first NPN current mirror output transistor in the differential input stage, and a second NPN current mirror output transistor in the output driver stage. A single compensation capacitor is connected between the first conductor and the third conductor. The compensation circuit compensates instability in the PNP and NPN current mirrors and also provides balanced responses of the PNP and NPN current mirror to 'glitches' in the power supply.