Laser driving open circuit detection method and detection circuit

Abstract

The invention discloses a laser driving open circuit detection method and a detection circuit, a driving circuit comprises a first triode and a second triode which can form a differential circuit, and the control ends of the first triode and the second triode are correspondingly connected with a first input end and a second input end respectively. One end of the first triode and one end of the second triode are connected to the first constant current source after being connected with a load ZL and a resistor Rterm respectively, the other end of the first triode and the other end of the second triode are connected to the second constant current source after being connected with a resistor R1 and a resistor R2 respectively, the output end of the second constant current source is grounded, and the laser is connected between one end of the second triode and the ground in parallel; the input voltage of the first input end and the input voltage of the second input end are equal and Itermgt; when Imod/2, the connection between the laser and the driving circuit is normal; on the contrary, when Iterm is smaller than or equal to Imod/2, the laser and the driving circuit are in an open-circuit state. The detection circuit has the advantages that normal work of the driving circuit is not affected, the judgment process is real-time and automatic, human intervention is not needed, and the detection circuit is simple in structure, easy to implement and low in power consumption.

Description

technical field [0001] The invention relates to a detection circuit, in particular to a laser driving open circuit detection method and a detection circuit. Background technique [0002] In the production process of the laser driver module (especially during the packaging and bonding process of the laser and the driver chip) or in the use stage of the laser driver module (due to external force factors or other factors), there will be disconnection between the driver chip and the laser. Phenomenon, so that the driving current cannot flow into the laser normally, and the laser does not emit light. Powering off the driver module and using a third-party testing tool can detect the open circuit between the driver chip and the laser, but this method is obviously time-consuming and resource-intensive. In order to reduce the detection time and cost of open-circuit bonding, it is necessary to design a detection circuit inside the driver chip that can automatically detect open-circui...

AI Technical Summary

Problems solved by technology

[0005] 1. Connecting a resistor in series with the output end of the laser will reduce the modulation current of the laser

[0006] 2. Connecting a resistor in series with the output end of the laser will consume a certain voltage margin and generate unnecessary energy consumption at the same time

[0007] 3. Connecting a resistor in series with the output end of the laser will affect the performance of the drive current (rise and fall time, amplitude, etc.)

[0008] 4. The presence of parasitic capacitance at the input of the DIFF_AMP amplifier will also affect the bandwidth of the drive circuit, which in turn affects the rise and fall time of the drive current, etc.

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