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:
Apr. 18, 2000
Filed:
Sep. 30, 1998
Dale A Heaton, Plano, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
The bandwidth of a bipolar complementary emitter follower unity gain buffer is proportionally dependent upon the idle current of the input stage (Q1, Q2) that drives the base nodes of the NPN (Q3) and PNP (Q4) emitter follower output transistors. A high bandwidth typically requires a high idle current. The bandwidth and slew rate of a unity gain buffer are improved without increasing the idle circuit by adding a circuit (Q9-Q12)to sense when a transient is occurring and increasing the positive or negative bias current only during the positive or negative transient. Shunt diodes (Q5, Q6) (base-emitter junctions) can be added across the input transistor emitters to shunt some of the input stage idle current into the opposing current source. This will reduce the idle current at the output stage and reduce the power dissipation of the input stage without sacrificing the available current to drive the base nodes of the output transistors.