MEMS Driver Circuit for Proof Mass Oscillation With Lower Power
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Solution Overview
Problem
Existing MEMS drivers for devices like gyroscopes face challenges in providing efficient, cost-effective, and low-power solutions for oscillating proof masses, which affect the accuracy and performance of motion detection in small mobile electronic devices.
Innovation Solution
A MEMS driver design that includes a high voltage amplifier with programmable gain blocks and a feedback path, capable of providing both closed-loop and open-loop output signals, which can modulate drive signals to maintain controlled oscillations of the proof mass without requiring external high-voltage storage components, thus reducing power consumption and silicon area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If external high-voltage storage components are used in MEMS drivers, then the device can provide sufficient drive voltage to oscillate the proof mass, but the silicon area and device complexity increase
Solution Approach 1:
The patent removes external high-voltage storage components from the system by integrating a charge pump circuit directly within the driver circuitry. This extraction of the external component and its relocation to an integrated implementation reduces silicon area while maintaining the necessary high-voltage drive capability for oscillating the proof mass
Solution Approach 2:
The patent combines the charge pump circuit with the driver circuitry into a single integrated unit. By merging the voltage generation function with the drive function, the system eliminates the need for separate external high-voltage storage components, thereby reducing both silicon area and device complexity while preserving full drive voltage capability
2Power
If external high-voltage storage components are used in MEMS drivers, then the device can provide sufficient drive voltage to oscillate the proof mass, but the device complexity increases
Solution Approach 1:
The patent combines the charge pump circuit with the driver circuitry into a single integrated unit. By merging the voltage generation function with the drive function, the system eliminates the need for separate external high-voltage storage components, thereby reducing device complexity while preserving full drive voltage capability
Solution Approach 2:
The integrated driver circuitry performs multiple functions: it generates high voltage through the charge pump, stores the generated voltage internally, and drives the proof mass oscillation. This multi-functionality eliminates the need for separate dedicated components, reducing overall device complexity
3Device complexity
If traditional MEMS driver designs are used, then the device structure is simpler, but power consumption increases
Solution Approach 1:
The patent implements a feedback mechanism where the driver circuitry monitors the oscillation state of the proof mass and adjusts the charge pump operation accordingly. This feedback control ensures that power is consumed only when necessary to maintain oscillation, reducing overall power consumption while maintaining the integrated device structure
Solution Approach 2:
The charge pump circuit operates in periodic cycles, charging the internal capacitor and then discharging to drive the proof mass oscillation. This periodic operation, controlled by the oscillation detection feedback, minimizes power consumption by keeping the charge pump inactive during non-oscillation periods while maintaining the simplified integrated structure
Data Source
AI summary
In an example, a driver for a micro-electro-mechanical-system (MEMS) device can include a first input configured to receive a first command signal including an oscillatory command signal, a second input configured to receive a second command signal including a bias command signal, and an amplifier configured to receive a high voltage supply, to provide, to the MEMS device, a closed-loop output signal responsive to both the first command signal and the second command signal in a first state, and to provide an open loop output signal configured to substantially span a voltage range of the high voltage supply in a second state.