MEMS Mirror Driver Circuits With PWM Error Compensation

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Solution Overview

Problem

Optical circuit switches using MEMS mirror arrays face challenges in ensuring accurate and precise voltage application to mirrors due to errors in driver circuits, leading to potential failures in connection formation between optical fiber communication paths.

Innovation Solution

The implementation of an error compensator to correct known errors in driver circuits, combined with the use of binary pulse-width modulation (PWM) signals and a low pass filter to achieve precise analog voltage levels, ensures accurate mirror rotation and connection establishment between optical ports.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional driver circuits are used to drive MEMS mirror arrays, then the device complexity is reduced, but the voltage application accuracy deteriorates due to circuit errors

Engineering Contradiction:

Improvevoltage application accuracyVSAvoiddriver circuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an error compensator as an intermediary component between the driver circuit and MEMS mirror array. This compensator measures the actual voltage applied to each mirror element and generates correction signals to compensate for driver circuit errors, thereby improving voltage application accuracy without requiring complete redesign of the driver circuits

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct voltage application through conventional driver circuits with a feedback-based control system that uses measurement and correction. Instead of relying solely on the driver circuit's inherent accuracy, the system measures actual voltage application and dynamically corrects errors through feedback control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If error compensation mechanisms are added to improve voltage accuracy, then the reliability of connection formation improves, but the device complexity increases

Engineering Contradiction:

Improveconnection formation reliabilityVSAvoiddriver circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements feedback control by measuring the actual voltage applied to each MEMS mirror element and using this information to generate correction signals. This feedback mechanism ensures that voltage application accuracy is maintained despite variations in driver circuit performance, thereby improving connection formation reliability

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent performs preliminary characterization of driver circuit errors during manufacturing or initial operation and stores compensation data for later use. This preliminary action allows the system to pre-compensate for known errors, improving reliability without requiring complex real-time correction mechanisms

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If precise analog voltage levels are achieved through PWM modulation and filtering, then the manufacturing precision of voltage control improves, but the device complexity increases due to additional components

Engineering Contradiction:

Improvevoltage control precisionVSAvoiddriver circuit complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces direct analog voltage generation with PWM (pulse-width modulation) digital control. By modulating the duty cycle of digital pulses and using low-pass filtering, the system achieves precise analog voltage levels through digital means, improving manufacturing precision while leveraging digital signal processing advantages

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution enhances the accuracy of voltage application to MEMS mirror arrays, minimizing errors and ensuring reliable connections between optical ports, even with imperfect driver circuits, thereby maintaining high bandwidth and low power consumption in optical circuit switches.

Implementation Method 1

binary pulse-width modulation (PWM) signals and a low pass filter to achieve precise analog voltage levels

Methodology Applied

Scientific EffectLow pass filtering: Filter (electronic)

Data Source

PatentUS8680894B1Precision driver circuits for micro-electro-mechanical system

Publication Date: 2014.03.25 CALIENT AI INC

AI summary

There is disclosed a driver circuits and method for driving a micro-electro-mechanical system. A driver circuit may include a converter to convert a digital input value into a pulse-width modulated signal with precise amplitude. A low pass filter may extract an average DC component of the pulse-width modulated signal. An amplifier may amplify the average DC component to provide an output voltage to drive the MEMS.