Circuit for light coupler

Abstract

The invention discloses an optical coupler circuit, which comprises an emitter circuit, a signal amplifying circuit and a receiving circuit, wherein the emitter circuit is used to emit optical signals according to voltage signals, the signal amplifying circuit is provided with an input end and an output end, and is used to amplify electric signals, the receiving circuit comprises a photo triode and a feedback resistance. The photo triode is provided with an electron collector, an emitter set and a base electrode, wherein the emitter set is coupled with the input end of the signal amplifying circuit, and is used to receive the optical signals, to transform the optical signals into the electric signals, and then send to the signal amplifying circuit. One end of the feedback resistance is coupled with the base electrode of the photo triode, and the other end thereof is coupled with the output end of the signal amplifying circuit for complementing the photo triode. The invention can improve the largest bandwidth by three to four times than an existing optical coupler owing to directly connecting the base electrode of the photo triode into the output end of the signal amplifying circuit through the feedback for realizing the complementation, therefore, increases the performances and the practicability.

Description

technical field [0001] The invention relates to an optocoupler circuit, in particular to an optocoupler which uses a simple circuit to improve performance. Background technique [0002] The optocoupler is used as one of the most commonly used devices for isolated switching power supplies. Because it has a good isolation effect on input and output electrical signals, it is used to transmit error signals at both ends of the isolation to achieve closed-loop control. [0003] Optical coupler (optical coupler, abbreviated as OC) is also called opto-isolator, referred to as optocoupler. An optocoupler uses light as a medium to transmit electrical signals. At present, it has become one of the most diverse and widely used optoelectronic devices. An optocoupler generally consists of three parts: light emission (such as a light-emitting diode), light reception (such as an optical transistor) and signal amplification (such as an amplifier). The input electrical signal drives the lig...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide an optocoupler circuit to solve the problems in the prior art that phototransistors require a larger collector-base region, which affects the bandwidth, resulting in instability of the optocoupler and poor practicability.

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