MEMS Rectifier Control With Voltage Clamping for Low-Loss Switching

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Solution Overview

Problem

Conventional AC-to-DC converters using diodes suffer from power loss due to a forward voltage drop, leading to heat generation and potential damage to circuit components, while MOSFET-based solutions are expensive and performance degrades at higher temperatures.

Innovation Solution

Implementing MEMS switches with a circuit topology and control strategy that includes current diverting and voltage clamp switches, achieving Zero-Voltage-Zero-Current turn-on and Zero-Current-Zero-Voltage turn-off to reduce stress during state transitions, thereby minimizing power loss and component costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional diodes are used for AC-to-DC conversion, then the circuit can perform rectification, but power loss occurs due to forward voltage drop

Engineering Contradiction:

Improvepower lossVSAvoidheat damage risk

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent changes the key parameter from diode forward voltage drop (0.7V) to MEMS switch on-resistance (10 times smaller), fundamentally altering the electrical characteristic to reduce power loss. This parameter change enables the system to maintain reliability while improving energy efficiency.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If MOSFET-based solutions are used to reduce power loss, then efficiency improves, but cost increases and performance degrades at high temperatures

Engineering Contradiction:

Improvepower lossVSAvoidcomponent cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent employs MEMS switches that are significantly cheaper than MOSFETs while providing superior performance. The MEMS technology offers a cost-effective alternative that maintains efficiency without the high temperature performance degradation associated with MOSFETs, making the system more economical for AC-to-DC conversion applications.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Loss of energy

If MEMS switches are used as ideal diodes, then power loss is reduced, but the switches cannot withstand hard switching at non-zero voltage

Engineering Contradiction:

Improvepower lossVSAvoidswitching stress tolerance

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent implements a control strategy that performs preliminary actions by detecting zero-crossing points of the AC waveform and timing the MEMS switch transitions to occur precisely when voltage is near zero. This preliminary timing action prevents hard switching conditions, allowing the MEMS switches to operate reliably with minimal power loss.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system employs feedback mechanisms to monitor the AC waveform and detect zero-crossing points, using this information to control the timing of MEMS switch transitions. This feedback ensures that switches change state only when voltage is near zero, protecting the MEMS devices from excessive stress while maintaining efficient operation.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12500514B2System and methods for using a MEMS switch as an ideal diode

Publication Date: 2025.12.16 DIGIQ POWER LTD

AI summary

A system and method for converting an input AC voltage of a voltage source into an output DC voltage is proposed. The proposed system and method include at least two MEMS switches coupled in parallel with a corresponding voltage clamp switch within a MEMS rectifier. The MEMS switches achieve Zero-Voltage-Zero-Current (ZVZC) Turn on and Zero-Current-Zero-Voltage (ZCZV) Turn off through the inclusion of at least one high frequency switch and a current diverting circuit which ensure that when the at least two MEMS switches transition between an on-state and off-state there is no voltage or current present in the at least two MEMS switches.