Optical Transmitter Gain Control for Test Systems

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Solution Overview

Problem

Existing test and measurement systems face challenges in adjusting gain and sensitivity for high-frequency electrical signals without compromising bandwidth and frequency response, often requiring complex adjustments and additional ASICs.

Innovation Solution

The system controls gain and sensitivity by adjusting the output power, wavelength, and line width of an optical transmitter, rather than modifying the optical-to-electrical converter, allowing for significant gain and sensitivity changes without degrading dynamic range, noise, or frequency response.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the gain of the optical-to-electrical converter is increased to improve sensitivity, then sensitivity is improved, but bandwidth and frequency response are reduced

Engineering Contradiction:

ImprovesensitivityVSAvoidbandwidth and frequency response

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

Instead of adjusting the gain of the optical-to-electrical converter to change sensitivity, the patent inverts the approach by adjusting the output power of the optical transmitter. This reverse control method allows sensitivity adjustment without affecting the bandwidth and frequency response characteristics of the converter, thereby resolving the technical contradiction.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the control parameter from the electrical domain (converter gain) to the optical domain (transmitter output power). By modifying the optical transmitter's output power, wavelength, and line width, the system achieves sensitivity adjustment while maintaining the electrical converter's bandwidth and frequency response characteristics unchanged.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a variable gain amplifier is used to adjust sensitivity, then sensitivity is adjustable, but system complexity increases

Engineering Contradiction:

Improveadjustable gain and sensitivityVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the gain control function from the optical-to-electrical converter domain and relocates it to the optical transmitter domain. This extraction eliminates the need for variable gain amplifiers and complex control circuits in the electrical domain, thereby reducing system complexity while maintaining adjustable sensitivity capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical/electrical variable gain amplifier system with an optical control system. By using optical parameters (power, wavelength, line width) to control sensitivity, the system eliminates complex electrical gain control circuits and ASICs, reducing overall system complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If gain adjustment is implemented in the electrical converter, then sensitivity is adjustable, but dynamic range and noise performance are compromised

Engineering Contradiction:

Improvesensitivity adjustmentVSAvoiddynamic range and noise performance

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent performs gain adjustment preliminarily in the optical domain before the optical-to-electrical conversion process. By adjusting the optical transmitter's output power, wavelength, and line width before conversion, the system achieves sensitivity adjustment without degrading the dynamic range and noise performance of the electrical converter, as these parameters remain optimized for their intended function.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables adjustable gain and sensitivity with reduced system complexity and noise, allowing for higher sensitivity without sacrificing bandwidth and frequency response, eliminating the need for complex gain control circuits and ASICs.

Implementation Method 1

The controller includes an optical transmitter with a laser

Methodology Applied

Scientific EffectLight emission from laser: Laser

Implementation Method 2

an optical sensor in an accessory head (104) that senses a measurement of a signal under test from a device under test (106) using a light beam from the optical transmitter (212)

Methodology Applied

Scientific EffectOptical detection:

Implementation Method 3

an optical receiver, and an optical-to-electrical converter

Methodology Applied

Scientific EffectOptical-to-electrical conversion: Photoelectric Effect

Data Source

PatentEP2887083B1Method of controlling electro-optical probe gain and sensitivity

Publication Date: 2019.02.20 TEKTRONIX INC

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AI summary

A method of controlling the gain or sensitivity of a test and measurement system. The test and measurement system includes a host, a controller with an optical transmitter and an optical receiver, optical-to-electrical converter, an accessory head, and a device under test. The method includes determining whether a gain or sensitivity adjustment of the test and measurement system is required, determining the amount of gain or sensitivity adjustment, and adjusting the output power of a laser of the optical transmitter in response to the determination of the gain or sensitivity adjustment of the test and measurement system.