Optical Modulator Driver Circuit With Single-Supply Amplifier Staging

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Solution Overview

Problem

Existing driver circuits for optical modulators in optical communication systems require multiple power supply voltages, leading to increased costs and power consumption, making it difficult to achieve lower power consumption operations while maintaining component and implementation efficiency.

Innovation Solution

A driver circuit design that connects multiple amplifiers to a single power supply voltage, with a higher voltage supplied to later-stage amplifiers, reducing power consumption by optimizing power supply connections and eliminating the need for separate power supply circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If multiple power supply voltages are used for different amplifiers, then power consumption is reduced, but device complexity and component costs increase

Engineering Contradiction:
Improvepower consumptionVSAvoidpower supply circuit complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent merges multiple power supply voltage requirements into a single power supply system. By cascading amplifiers where the power supply terminal of one amplifier connects to the ground terminal of the next amplifier, the system achieves multiple effective voltage levels from a single power supply, reducing component complexity while maintaining energy efficiency.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent segments the power supply function across multiple amplifier stages. Each amplifier operates at a different voltage level relative to ground, with intermediate stages using the output of previous stages as their reference. This segmentation allows each amplifier to operate optimally at its required voltage while using a unified power supply architecture.

Inventive Principle:
Principle #1Segmentation

2Use of energy by moving object

If multiple power supply voltages are used for different amplifiers, then power consumption is reduced, but manufacturing costs increase

Engineering Contradiction:
Improvepower consumptionVSAvoidmanufacturing cost
Core Design Contradiction:
Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The patent combines multiple power supply requirements into a single power supply component. This reduces the bill of materials and simplifies manufacturing processes, as fewer discrete power supply components need to be sourced, mounted, and tested, thereby reducing manufacturing costs while maintaining the power consumption benefits of multiple voltage levels.

Inventive Principle:
Principle #5Merging (Combining)

3Device complexity

If a single power supply voltage is used for all amplifiers, then device complexity is reduced, but power consumption increases

Engineering Contradiction:
Improvepower supply circuit complexityVSAvoidpower consumption
Core Design Contradiction:
Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent introduces dynamic voltage referencing where each amplifier stage operates with a different voltage reference point. The ground terminal of one amplifier becomes the power supply terminal for the next, creating a dynamic voltage hierarchy that reduces power consumption in later stages while maintaining a simple single-power-supply external interface.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3439176B1Driver circuit and optical transmitter
Publication Date: 2021.12.15 NIPPON TELEGRAPH & TELEPHONE CORP
  • EP3439176B1 patent drawingFigure 1
  • EP3439176B1 patent drawingFigure 2~3
  • EP3439176B1 patent drawingFigure 4

AI summary

A positive-side power supply terminal (1-1a) of a differential amplifier (1-1) is connected to a positive-side power supply line (L1). A negative-side power supply terminal (1-2b) of a differential amplifier (1-2) is connected to a negative-side power supply line (L2). A negative-side power supply terminal (1-1b) of the differential amplifier (1-1) and a positive-side power supply terminal (1-2a) of the differential amplifier (1-2) are connected to each other. A final-stage amplifier (2) is connected between the positive-side power supply line (L1) and the negative-side power supply line (L2).