Optical Power Meter Circuit With Bootstrap and Distortion Compensation

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Solution Overview

Problem

Existing optical power measurement circuits face challenges in achieving high dynamic range and fast measurement speeds due to gain switching-induced glitches and frequency-dependent distortions, particularly at low power levels.

Innovation Solution

The proposed solution involves a linear amplification circuit with multiple transimpedance operational amplification lanes, a bootstrap circuit to reduce photodiode capacitance effects, and a compensator circuit to monitor and subtract transient distortions, thereby enhancing bandwidth and reducing measurement errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If gain switching is used to extend dynamic range, then measurement range increases, but glitches and transient effects are introduced

Engineering Contradiction:

Improvedynamic rangeVSAvoidmeasurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The measurement system is divided into multiple parallel transimpedance amplification lanes, each handling a specific gain range. This segmentation allows the system to achieve extended dynamic range without gain switching, as each lane operates continuously in its optimal range, eliminating glitches and transient effects while maintaining high measurement accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically selects which amplification lane to use based on the input signal level, but within each lane the transimpedance amplifier operates in a static, continuous mode without switching. This dynamic lane selection combined with static operation within lanes resolves the contradiction by providing adaptability across wide dynamic ranges while maintaining reliability through continuous operation.

Inventive Principle:

Principle #15Dynamics

2Speed

If logarithmic transimpedance amplification is used, then high speed performance is achieved, but frequency-dependent distortions and bandwidth limitations occur

Engineering Contradiction:

Improvescan speedVSAvoidmeasurement linearity

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The system changes the transimpedance gain parameter by selecting different amplification lanes with different fixed gain values, rather than using a single logarithmic amplification circuit. Each lane provides linear amplification with optimized bandwidth, achieving high scan speeds while maintaining measurement linearity and avoiding frequency-dependent distortions through parameter optimization rather than logarithmic transformation.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If multiple gain settings are implemented, then dynamic range extends, but device complexity increases

Engineering Contradiction:

Improvedynamic rangeVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Multiple transimpedance amplification lanes are merged into a single integrated circuit structure, sharing common components such as the photodiode detector, bootstrap circuit, and compensation circuitry. This merging approach extends dynamic range through multiple gain settings while minimizing the increase in device complexity by reusing common elements across lanes rather than implementing completely separate circuits for each gain setting.

Inventive Principle:

Principle #5Merging (Combining)

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 configuration allows for increased scan speeds and improved measurement accuracy by minimizing frequency-dependent distortions and errors, particularly at lower power levels, effectively addressing the limitations of previous multiscale amplification circuits.

Implementation Method 1

a photodiode detector to produce an electrical current dependent upon the intensity of light incident thereupon

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS11815395B1High-dynamic optical power meter comprising plural transimpedance operational amplifiers, a bootstrap circuit to suppress a voltage across a photodiode detector and a compensation circuit

Publication Date: 2023.11.14 EXFO OPTICS SAS

AI summary

There is proposed an optical power measurement circuit and an optical power meter which use a linear amplification circuit based on multiple transimpedance operational amplification lanes and which add a bootstrap circuit and a compensator circuit. 1) The bootstrap is used to reduce the effect of the photodiode capacitance and increases the amplifier's bandwidth. 2) The compensator circuit monitors the photodiode's voltage and reproduces its transient distortions, to then subtract it from the output and thereby reduce the measurement error.