Photocurrent monitoring circuit for transimpedance amplifier

Abstract

The photocurrent monitoring circuit (PMC) includes non-linear sampling circuit, negative feedback amplifier, sampling mirror image circuit, current mirror, and I / V switching circuit etc. The non-linear sampling circuit consists of transistor Q1 and resistance R2. The negative feedback amplifier is composed of amplifier A2 and field effect tube M8. The sampling mirror image circuit is composed of transistor Q2 and resistance R3. Current mirror, and I / V switching circuit include field effect tubes M4, M5, M6, M7 and resistance R4. Being able to monitor the input photocurrent in large dynamic range, PMC still keeps high precision. When PMC monitors the input photocurrent in large dynamic range, normal operation of main body of magnifier is not influenced.

Description

technical field [0001] The invention relates to the field of optical communication, in particular to a photocurrent monitoring circuit for a transimpedance amplifier. Background technique [0002] Researchers at home and abroad have done a lot of research on transimpedance amplifier TIA. If the TIA used in the optical communication field has a photocurrent monitoring function, it will greatly facilitate the user's system design. [0003] Existing photocurrent monitoring circuits mostly use linear sampling circuits for monitoring circuits. The disadvantage of this type of sampling circuit is that if the sensitivity of the sampling circuit is set low, when a small signal photocurrent is input, because the signal amplitude is very small, it will The accuracy of the output monitoring signal is very low and the error is large; if the sensitivity of the sampling circuit is set higher, when a large signal photocurrent is input, a considerable sampling voltage will be generated at ...

AI Technical Summary

Problems solved by technology

[0003] Existing photocurrent monitoring circuits mostly use linear sampling circuits for monitoring circuits. The disadvantage of this type of sampling circuit is that if the sensitivity of the sampling circuit is set low, when a small signal photocurrent is input, because the signal amplitude is very small, it will The accuracy of the output monitoring signal is very low and the error is large; if the sensitivity of the sampling circuit is set higher, when a large signal photocurrent is input, a considerable sampling voltage will be generated at both ends of the sampling circuit, which may cause the PIN to fail to work normally.

Therefore, it cannot adapt to the photocurrent input signal with a large dynamic range.

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