A MEMS gyroscope measures angular rotation rate using the Coriolis effect on a vibrating silicon proof mass. No spinning parts, no bearings, no wear. Just a chip smaller than a fingernail that detects rotation to better than 0.01 degrees per second.
This article covers how a MEMS gyroscope works, the key performance parameters engineers use to select one, and where they appear across automotive, aerospace, industrial, and consumer applications.
A MEMS gyroscope is a microelectromechanical sensor that measures the rate of angular rotation in degrees per second or radians per second by detecting the Coriolis force acting on a silicon proof mass vibrating at its resonant frequency.
Unlike a conventional spinning gyroscope that uses angular momentum to resist rotation, a MEMS gyroscope has no rotating parts at all. The sensing element is a microscopic mass driven into oscillation by electrostatic forces, and Coriolis physics does the rest.
What Is a MEMS Gyroscope and How It Differs from a Traditional Gyroscope
A traditional mechanical gyroscope maintains orientation using the angular momentum of a rapidly spinning rotor. The rotor resists changes in its spin axis, giving navigation instruments a stable reference.
These devices work well but require precision bearings, constant motor power, and expensive manufacturing tolerances.
A MEMS gyroscope replaces the spinning rotor with a proof mass vibrating at its resonant frequency, typically 10 to 40 kHz. When the chip rotates, the Coriolis effect deflects the vibrating mass perpendicular to both the vibration and the rotation axis.
That deflection, measured by capacitive electrodes, is proportional to the angular rate.
The result is a sensor costing under five dollars that runs on microamps of standby current and survives 10,000g shock events.
The same Coriolis physics that governs ocean currents and weather patterns makes this possible at microscopic scale.
MEMS gyroscopes are almost always paired with a 3-axis accelerometer to form an Inertial Measurement Unit (IMU). The accelerometer provides linear acceleration and gravity reference; the gyroscope provides angular rate.
Together they give a complete 6-axis motion picture for industrial automation systems and navigation processors.
MEMS Gyroscope Working Principle: The Coriolis Effect Explained
The Coriolis effect is an apparent force that acts on any object moving within a rotating reference frame. On Earth, it deflects winds to the right in the northern hemisphere and left in the southern.
Inside the chip, it deflects a vibrating proof mass sideways when the chip rotates.
The proof mass is driven into oscillation along the drive axis by electrostatic comb drives at its resonant frequency. This is called the drive mode.
When the chip rotates at angular rate omega (ω), the Coriolis force acts on the moving proof mass perpendicular to both the drive velocity and the rotation axis. This is the sense mode.
The Coriolis force is given by:
A sense displacement of 0.7 picometres is smaller than a hydrogen atom's radius (53 pm). Detecting it requires differential capacitive sensing with on-chip charge amplifiers and lock-in detection at the drive frequency to reject out-of-band noise.
Drive Mode and Sense Mode: Inside the MEMS Gyroscope Structure
Drive Mode (Actuation)
Electrostatic comb drives oscillate the proof mass at its resonant frequency, typically 10 to 40 kHz. A phase-locked loop (PLL) on the same chip locks this frequency precisely. Higher drive amplitude and frequency improve sensitivity.
Sense Mode (Detection)
The Coriolis force deflects the proof mass perpendicular to the drive direction. Differential capacitive electrodes detect this deflection. A synchronous demodulator extracts the signal at the drive frequency to reject noise.
Tuning Fork Design
Two proof masses driven in anti-phase. Coriolis forces act in opposite directions on each mass, doubling the sense signal while cancelling common-mode vibration and linear acceleration. The most widely used architecture in production today.
Ring Resonator Design
A silicon ring vibrates in an elliptical mode. Rotation shifts the vibration pattern around the ring, detected by electrodes at fixed positions. Lower sensitivity than tuning fork but more symmetric and less sensitive to fabrication mismatch.
Key MEMS Gyroscope Performance Parameters
| Parameter | Typical Range | What It Means | Selection Guidance |
|---|---|---|---|
| Full-Scale Range | ±100 to ±2000 deg/s | Maximum angular rate the sensor measures without clipping | Choose 2× expected peak rate; drones need ±2000 deg/s, navigation needs ±100 deg/s |
| Sensitivity | 3 to 80 mV per deg/s | Output voltage change per unit angular rate | Higher sensitivity for slow, precise motion; lower for fast rotation |
| Noise Density | 0.003 to 0.1 deg/s/√Hz | RMS noise per unit bandwidth. Multiply by sqrt(BW) for total noise. | Below 0.01 deg/s/√Hz for navigation; up to 0.1 for attitude stabilization |
| Angle Random Walk (ARW) | 0.01 to 1 deg/√hour | Accumulated angle error from noise when integrating rate over time | Below 0.1 deg/√hour for dead-reckoning navigation; any for rate sensing |
| Bias Instability | 0.1 to 10 deg/hour | Slow drift of the zero rate output over time and temperature | Below 1 deg/hour for precision IMU; up to 10 deg/hour for attitude hold |
| Bandwidth | 10 to 500 Hz | Frequency range over which the sensitivity is flat within ±3 dB | Match to your control loop update rate; drones typically need 200 Hz or above |
| Zero Rate Output (ZRO) | ±5 to ±50 mV offset | Output voltage when angular rate is exactly zero. Must be subtracted in firmware. | Lower ZRO means less firmware calibration work; always calibrate at rest before use |
MEMS Gyroscope Noise and Coriolis Force Calculator
MEMS Gyroscope Applications
MEMS Gyroscope vs Accelerometer: Understanding the Difference
| Property | MEMS Gyroscope | MEMS Accelerometer |
|---|---|---|
| Measures | Angular rate (deg/s or rad/s) | Linear acceleration (g or m/s²) |
| Physical principle | Coriolis force on vibrating proof mass | Inertial force on suspended proof mass |
| Static orientation | Cannot determine tilt from gravity | Can measure tilt from gravity vector |
| Dynamic rotation | Directly measures rotation rate | Cannot separate rotation from linear acceleration |
| Integration output | Integrate rate over time to get angle | Integrate acceleration to get velocity, then position |
| Drift behaviour | Angle error grows with time (ARW) | Position error grows as time squared |
| Why combined in IMU | Provides fast, accurate short-term rotation reference | Provides long-term gravity and tilt reference to correct gyro drift |
Selecting a MEMS Gyroscope: Right Approach vs Common Pitfalls
✅ Correct Approach
- Set full-scale range to 2× your expected peak angular rate to avoid output clipping
- Calculate required noise: noise density × sqrt(bandwidth) must be well below your minimum detectable rate
- Check bias instability for long-duration dead-reckoning tasks; short-term stabilization is noise limited, long-term navigation is bias limited
- Choose SPI interface for high update rates above 1 kHz; I2C is adequate for slower control loops
- Always calibrate zero rate output (ZRO) at rest before deployment; temperature affects ZRO significantly
❌ Common Mistakes
- Selecting ±250 deg/s range for a drone application where flick rolls reach ±1800 deg/s
- Integrating raw rate output without bias subtraction, causing angle error that grows to tens of degrees in minutes
- Ignoring vibration isolation: high-frequency mechanical vibration from motors aliases into the gyroscope output as a false rate signal
- Confusing angular rate (deg/s) with angle (deg): a gyroscope output needs time integration to give angle
- Using a consumer grade part with 10 deg/hour bias instability for a navigation task that needs 1 deg/hour stability
Watch: How a MEMS Gyroscope Works
MEMS Gyroscope Questions Engineers Ask
External References
- MEMS Gyroscope Precision Inertial Sensing — Analog Devices
- How to Select MEMS Gyroscopes — STMicroelectronics (PDF)
What We Learn Today
- A MEMS gyroscope measures angular rotation rate using the Coriolis force on a vibrating silicon proof mass, with no spinning parts
- Coriolis force formula: F = 2 × m × v × ω; at 100 deg/s this produces about 3.5 pN of force on a 1 microgram mass
- The proof mass is driven at resonance (10 to 40 kHz) in drive mode; Coriolis deflection is detected by capacitive electrodes in sense mode
- Key parameters: noise density (deg/s per sqrt Hz), angle random walk (deg per sqrt hour), bias instability (deg/hour), and full-scale range
- RMS noise = noise density × sqrt(bandwidth); integrating this noise gives angle error that grows with the square root of time
- Gyroscopes measure rate, not angle: always integrate the output to get angle, after subtracting the zero-rate offset
- Combined with an accelerometer in an IMU, the gyroscope handles fast rotation; the accelerometer corrects long-term drift using gravity as a reference