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:
Sep. 07, 1999
Filed:
Mar. 19, 1998
Carl Keith Sawtell, San Jose, CA (US);
Astec International Limited, , HK;
Abstract
In an electronic circuit having an input stage, an output stage having an output voltage, and a feedback element including a coupler having a transmitter coupled to said output stage and a receiver coupled to said input stage, said receiver being galvanically isolated from said transmitter, said transmitter sending an output signal that is a function of said output voltage to said receiver, said receiver generating a receiver output in response to receiving said output signal, a feedback control circuit for said feedback element, said feedback control circuit comprising: a transmitter drive circuit coupled to said transmitter for adjusting said output signal as a function of said output voltage, said transmitter drive circuit comprising an error signal generation stage, said error signal generation stage using a voltage that is a function of the output voltage to generate a feedback control signal, and a non-linear stage, said non-linear stage outputting a transmitter drive signal to said transmitter as a function of said feedback control signal, wherein said non-linear stage non-linearly adjusts said transmitter drive signal as a function of said output voltage to compensate for variations in the ratio of said receiver output to said transmitter drive signal; and a receiver output circuit, said receiver output circuit receiving and amplifying said receiver output and coupling said amplified output to said input stage and causing said receiver to operate at a substantially fixed bias operating current. In a preferred embodiment, the non-linear stage is an exponential transconductance stage for exponentially adjusting the transmitter drive signal, said coupler comprises an optocoupler having a light emitting diode (LED) as said transmitter and a phototransistor as said receiver, said phototransistor being optically coupled to said LED, said LED having an anode and a cathode and said phototransistor having an emitter terminal and a collector terminal.