APD protection circuit and device

Abstract

The invention discloses an APD protection circuit and device. The APD protection circuit comprises a voltage output circuit, a current-limiting resistor, a current detection circuit and a rapid discharge circuit, wherein an input end of the voltage output circuit is connected with a system power supply end, an output end of the voltage output circuit is connected with an input end of the current detection circuit through the current-limiting resistor, an output end of the current detection circuit is connected with a negative electrode of an APD, a positive electrode of the APD is grounded, the input end of the current detection circuit is grounded through the rapid discharge circuit, and a signal output end of the current detection circuit is connected with a controlled end of the rapid discharge circuit; the current detection circuit is used for detecting light current of the APD and sending a corresponding direct-current voltage signal; and the rapid discharge circuit is used for connecting the quick discharge circuit to the rear end of the current-limiting resistor to carry out bypass discharge when the direct-current voltage signal reaches a conduction threshold value. According to the APD protection circuit and the device, rapid discharge can be carried out when the received optical power is too large, the APD is prevented from being damaged by relatively large optical current, overload protection of the APD is realized, and normal operation of the APD can be maintained.

Description

technical field [0001] The invention relates to the field of optical module circuits, in particular to APD protection circuits and devices. Background technique [0002] In existing optical modules, the photoelectric signal conversion device commonly used is an avalanche photodiode (APD). When using an APD for photoelectric conversion, a high bias voltage needs to be applied to one end of the APD. When the input optical signal is large or strong, a large photocurrent will be generated on the APD. When the photocurrent exceeds the maximum current allowed by the APD die, the APD will be damaged. [0003] In the prior art, a current limiting resistor is usually set on the current loop where the APD is located to generate a larger voltage drop when the current increases to reduce the bias voltage on the APD, so as to avoid excessive current when the strong light signal illuminates the APD. . However, because a large amount of charge is stored in the decoupling capacitor, whe...

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Problems solved by technology

[0005] The main purpose of the present invention is to provide an APD protection circuit and device, which aims to solve the problem that the APD cannot work normally when the APD is overloaded in the prior art

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