| 摘要 |
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.
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