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:
Aug. 15, 1995
Filed:
Jun. 09, 1994
David J Kunst, Tucson, AZ (US);
Stuart B Shacter, Tucson, AZ (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A complementary transistor class AB output stage (200) utilizes a complementary pair of output drivers (220, 222) connected in series between the power supply rails (210, 216) to furnish the stage output. An output driver (206) is a composite pair of transistors in a Darlington configuration, which boosts the current gain and input resistance of the output stage. Bases of the output drivers are connected by a complementary pair of parallel connected drivers (226, 228), which function as common base level shifters. Quiescent bias of the output drivers is achieved by a pair of constant current transistors (232, 238) that are operated as complementary current mirrors. Inputs to the mirrors are relatively low current sink (252) and source (250) supplies. A level shifter and its corresponding current mirror are configured so that base currents flowing therein, which may be variable due to temperature and process variations, are generally shunted away from the current mirrors and toward an output driver to maintain mirrored currents and assist output drive.