Signal intensity detection circuit of trans-impedance amplifier

Abstract

The invention provides a signal intensity detection circuit of a trans-impedance amplifier. The signal intensity detection circuit obtains a sampled signal from the output photocurrent IPD (Insertion Phase Delay) of a photoelectric diode (PD), and simultaneously separates the high-frequency component and the low-frequency component of the sampled signal from each other; the high-frequency component IAC enters a main trans-impedance amplifier module through a coupling capacitor C1, while the low-frequency component IDC is the signal intensity indication of the trans-impedance amplifier; and the main trans-impedance amplifier module achieves the trans-impedance amplification function of amplifying a tiny photocurrent to a voltage signal. The signal intensity detection circuit provided by the invention directly samples the input photocurrent signal and the detection result obtained in this way is quite correct; an adaptive nonlinear sampling circuit is adopted so that the detection accuracy is improved; simultaneously, the dynamic range of the input photocurrent is very wide; and the high-frequency component is separated from the photocurrent signal and fed into the main trans-impedance amplifier module; and therefore, the influence of the low-frequency component on the direct-current working point of the main trans-impedance amplifier module in the traditional structure is avoided.

Description

technical field [0001] The invention relates to a signal strength detection circuit, in particular to a signal strength detection circuit of a transimpedance amplifier. Background technique [0002] The optical receiver is an important part of the optical fiber transmission system. Its function is to convert and amplify the attenuated weak optical pulse signal, and output it as a differential voltage signal. Transimpedance amplifiers are usually used as preamplifiers for optical receivers. [0003] The signal strength detection circuit of the existing transimpedance amplifier generally samples at the negative end of the photodiode PD, which will cause certain limitations in the application environment and cannot be adapted to the APD application. Since the input photocurrent ranges from uA level to mA level, and the change range is close to 40dBm, the traditional linear sampling method reduces the dynamic range and accuracy of signal strength detection to a certain extent. ...

AI Technical Summary

Problems solved by technology

[0003] The signal strength detection circuit of the existing transimpedance amplifier is generally sampled at the negative end of the photodiode PD, which will cause certain limitations in the application environment and cannot be adapted to APD applications

Since the input photocurrent ranges from uA level to mA level, and the range span is close to 40dBm, the traditional linear sampling method reduces the dynamic range and accuracy of signal strength detection to a certain extent.

Images