MEMS Oscillator Interface for Temperature Compensation and Low Noise

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Solution Overview

Problem

High precision timing devices face challenges in accurately compensating for temperature-induced frequency offsets, leading to instability in timing signals over varying temperatures, and existing solutions often introduce voltage switching noise that affects sensitive timing generation circuitry.

Innovation Solution

Integration of a MEMS resonator and temperature transducer within a small form-factor IC package that outputs both timing signals and temperature-dependent frequency compensation data, using a multi-function interface for efficient temperature data transmission and control, and implementing current-mode signaling to minimize voltage switching noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If voltage-mode signaling is used for temperature data transmission, then data transmission capability is improved, but voltage switching noise increases and interferes with timing generation circuitry

Engineering Contradiction:

Improvetemperature data transmissionVSAvoidvoltage switching noise

Core Design Contradiction:

Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The patent replaces voltage-mode signaling with current-mode signaling for temperature data transmission. This substitution changes the signaling mechanism from voltage-based to current-based, thereby eliminating voltage switching noise while maintaining data transmission capability. The current-mode interface uses current sources and sinks to represent logic levels, which does not generate the same voltage transients as voltage-mode signaling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If multiple separate pins are used for clock output and temperature data output, then signal transmission quality is improved, but device package complexity and pin count increase

Engineering Contradiction:

Improvesignal transmission qualityVSAvoidpackage pin count

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a multi-function interface that can operate in different modes: voltage-mode for high-speed data transmission, current-mode for low-noise temperature data transmission, and bidirectional communication. This single interface replaces what would otherwise require multiple separate pins, reducing package complexity while maintaining signal transmission quality through mode-appropriate signaling.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The interface is designed to dynamically switch between different operating modes (voltage-mode, current-mode, bidirectional) based on the communication requirements. This dynamic capability allows the same physical interface to optimize performance for different functions, eliminating the need for dedicated pins for each function.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If temperature compensation data is not provided, then device simplicity is maintained, but timing signal accuracy degrades over varying temperatures

Engineering Contradiction:

Improvedevice simplicityVSAvoidtiming signal accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent incorporates a temperature sensor that continuously monitors the operating temperature and provides feedback in the form of temperature compensation data. This feedback mechanism allows the system to adjust for temperature-induced frequency variations in the MEMS resonator, maintaining timing signal accuracy across varying temperatures without significantly increasing device complexity.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The oscillator circuit includes integrated temperature sensing and compensation capabilities that automatically adjust the timing signal based on measured temperature conditions. This self-service approach eliminates the need for external temperature compensation circuits, maintaining device simplicity while improving timing accuracy over temperature.

Inventive Principle:

Principle #25Self-service

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

Enables accurate temperature compensation of timing signals, reducing noise interference and maintaining high precision across a wide temperature range while maintaining a compact and low-pin-count package.

Implementation Method 1

a MEMS resonator and temperature transducer integrated within a small form-factor integrated circuit (IC) package that outputs both a timing signal according to mechanical vibration of the MEMS resonator

Methodology Applied

Scientific EffectMechanical vibration: Vibration

Implementation Method 2

a MEMS (microelectromechanical system) resonator and temperature transducer—generally a temperature-to-digital converter (TDC)

Methodology Applied

Scientific EffectTemperature-to-digital conversion:

Data Source

PatentUS10833632B1Temperature-reporting oscillator

Publication Date: 2020.11.10 SITIME CORP

AI summary

In an integrated circuit device having a microelectromechanical-system (MEMS) resonator and a temperature transducer, a clock signal is generated by sensing resonant mechanical motion of the MEMS resonator and a temperature signal indicative of temperature of the MEMS resonator is generated via the temperature transducer. The clock signal and the temperature signal are output from the integrated circuit device concurrently.