Method for calculating APD breakdown voltage and circuit thereof

Abstract

The present invention provides a method for calculating APD breakdown voltage and a circuit thereof. The method comprises the following steps: 1, adding reserve voltage Vapd on an APD in a condition without light; 2, dark current (Idark) generated by the APD flows into a trans-resistance amplifier (3) after passing through a current mirror (2); 3, reversely calculating the dark current (Idark) through output voltage (Vo) of the trans-resistance amplifier (3); and 4, determining whether the dark current (Idark) of the APD is equal to 10 [Mu]A or not, if the dark current (Idark) of the APD is equal to 10 [Mu]A, allowing the APD at present to be the breakdown voltage of the APD, or else, repeatedly setting the Vapd, and returning back to the step 3. The method for calculating APD breakdown voltage and the circuit thereof can accurately find the Vbr of the APD so as to find reasonable reverse direction work voltage Vapd, are good in precision, efficiency and consistence, improve the yield rate of an optical module, improve production efficiency and reduce production cost.

Description

technical field [0001] The invention relates to an APD (avalanche photodiode), in particular to a method and circuit for calculating the breakdown voltage of the APD. Background technique [0002] In the production process of optical modules using APD as the receiving end, the correct setting of the APD working point can ensure the sensitivity and overload of the optical module receiving end to meet the industry's index requirements. A reasonable APD reverse working voltage Vapd is usually closely connected with the breakdown voltage Vbr of the APD (usually Vapd=Vbr-X), so finding the Vbr of the APD is crucial to setting the working voltage of the APD. [0003] In the existing methods of debugging optical modules, Vapd is usually adjusted inversely according to the best sensitivity of the test module, but Vapd at the best sensitivity point is usually a range (such as figure 1 shown), and the sensitivity of each APD is different, so the consistency of the module Vapd voltage...

AI Technical Summary

Problems solved by technology

[0003] In the existing methods of debugging optical modules, Vapd is usually adjusted inversely according to the best sensitivity of the test module, but Vapd at the best sensitivity point is usually a range (such as figure 1 shown), and the sensitivity of each APD is different, so the consistency of the module Vapd voltage cannot be guaranteed

At the same time, if some APDs have poor sensitivity and do not meet the requirements, it takes a lot of time to debug and select during production, and the production efficiency is low.

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