MEMS Resonator Kick-Start Circuit for Fast Oscillator Startup
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Solution Overview
Problem
MEMS oscillators experience significant startup delays, which hinder 'on-demand' functionality in battery-powered devices, leading to increased power consumption and delayed system responsiveness.
Innovation Solution
A system and method that utilize a positive feedback loop with capacitance-to-voltage circuitry and gain circuitry to provide energy at the natural frequency of the MEMS resonator, including a kick-start mechanism with a series of pulses near the resonant frequency to rapidly initiate oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional MEMS oscillator startup methods are used, then the system can eventually reach oscillation, but the startup time is excessively long causing delayed system responsiveness
Solution Approach 1:
The patent applies preliminary action by pre-charging capacitors (C1, C2) to specific voltage levels (VDD and VSS) before the oscillator is activated. This preliminary preparation of energy storage elements enables the oscillator to immediately begin oscillating at full amplitude when the enable signal is asserted, eliminating the gradual startup phase and achieving instantaneous activation.
Solution Approach 2:
The patent employs periodic action through the use of kick-start pulses applied to the resonator. These periodic voltage pulses are applied during the initial phase to rapidly build up oscillation amplitude, providing the necessary energy input in a structured temporal pattern that accelerates the startup process significantly compared to continuous low-level excitation.
2Loss of time
If the MEMS oscillator is kept continuously running to avoid startup delays, then system responsiveness is improved, but power consumption increases
Solution Approach 1:
The patent enables the oscillator to be completely powered down when not in use, with capacitors discharged and no energy consumption. Upon activation, the pre-charging mechanism instantly restores full oscillation without requiring a warm-up period, thus achieving both zero power consumption during idle states and immediate responsiveness during active states.
Solution Approach 2:
The patent implements dynamic operation by allowing the oscillator to transition between completely off and fully on states. The circuit architecture supports rapid switching between these states through the enable signal control of the capacitive sensing circuitry and kick-start mechanism, eliminating the need for intermediate idle states and enabling optimal power-performance tradeoff.
3Loss of time
If a kick-start mechanism with multiple pulses is used to rapidly initiate oscillation, then startup time is reduced, but device complexity increases
Solution Approach 1:
The patent achieves multi-functionality by using the same capacitive sensing circuitry and amplifier for both normal oscillation detection and kick-start pulse generation. The enable signal simultaneously controls capacitor charging, kick-start pulse application, and oscillator activation, consolidating multiple functions into existing circuit blocks without adding dedicated startup circuitry.
Solution Approach 2:
The patent implements self-service through the automatic discharge of capacitors C1 and C2 through resistors R1 and R2 when the enable signal is low. The circuit automatically prepares itself for the next activation cycle without external intervention, and the kick-start mechanism automatically applies the correct number and amplitude of pulses based on the resonator's natural response, eliminating the need for complex external control logic.
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
Significantly reduces startup time for MEMS oscillators, allowing for efficient power management by enabling quick activation and deactivation, thereby reducing overall energy consumption and minimizing delays in device functionality.
Implementation Method 1
determining a natural frequency of the MEMS resonator; generating a kick signal having a fundamental frequency near the natural resonant frequency of the MEMS resonator
Implementation Method 2
utilize a positive feedback loop with capacitance-to-voltage circuitry and gain circuitry to provide energy at the natural frequency of the MEMS resonator
Data Source
AI summary
A MEMS resonator system comprises a MEMS resonator, kick start circuitry, feedback circuitry, an oscillator, and a switch. The MEMS resonator system is configured to provide a pulsed kick-start signal having a frequency and period such that energy delivered to the MEMS resonator is optimized in a short period of time, resulting is reduced oscillator startup time. The MEMS resonator system is configured to switch out the kick-start signal when the MEMS resonator oscillation has been achieved, and switch in feedback circuitry to maintain the MEMS resonator in a state of oscillation.