Optical Module Bias Pin Control via PNP Triode Inversion

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Solution Overview

Problem

In WDM-based PON systems, the existing laser transmitter driver chips cannot control the DBR laser to emit light effectively due to the SINK mode operation, where the negative terminals of the laser transmitter and DBR laser are grounded, limiting the ability to select different wavelengths and stabilize current flow.

Innovation Solution

The optical module incorporates a laser transmitter driver chip with a bias pin, a laser transmitter, a DBR raster, and PNP or NPN triodes, where the emitters are connected to the power source, and the collectors and bases are connected to the bias pin, allowing the level of the bias pin to control the emission of light by switching the triodes on or off, thereby enabling current flow to the positive terminal of the laser transmitter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the negative terminals of the laser transmitter and DBR laser are grounded in SINK mode operation, then the existing driver chip configuration is maintained, but the ability to control the DBR laser to emit light effectively is limited and wavelength selection is restricted

Engineering Contradiction:

Improvecontrol effectivenessVSAvoidwavelength selection capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent inverts the conventional SINK mode grounding configuration by connecting the positive terminal of the DBR laser to ground and the negative terminal to the driver chip output. This inversion enables effective control of the DBR laser emission and allows for wavelength selection through the driver chip, resolving the limitations of the traditional grounded negative terminal configuration

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the electrical connection parameters of the DBR laser from SINK mode (grounded negative terminal) to a configuration where the positive terminal is grounded. This parameter change enables the driver chip to effectively control the laser current and wavelength, improving both control effectiveness and adaptability

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If triodes are added to control current flow to the bias pin, then precise control of laser emission is achieved, but the device complexity increases

Engineering Contradiction:

Improvelaser emission control precisionVSAvoidcircuit structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent introduces triodes as intermediary switching elements between the driver chip and the laser transmitter. These triodes act as controlled switches that precisely regulate current flow to the bias pin, enabling accurate control of laser emission while maintaining a manageable circuit structure through their compact integration

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10008825B2Optical module

Publication Date: 2018.06.26 HISENSE BROADBAND MULTIMEDIA TECH

AI summary

The disclosure provides an optical module. In the optical module, emitters of a first PNP type triode and a second PNP type triode connected with a power source are high-level always, when a bias pin of a laser transmitter driver chip is high-level, bases of the two PNP type triodes are both high-level and in an OFF state, no current flows to the bias pin and a laser transmitter, and the laser transmitter does not emit light; when the bias pin of the laser transmitter driver chip is low-level, the bases of the two PNP type triodes are both low-level and in an ON state, the current flows to the bias pin and flows from a positive terminal of the laser transmitter, and the laser transmitter emits light.