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Application of Current Frequency Conversion Module in Inertial Sensor System
The charge-integration I/F module plays a crucial role in inertial sensor (especially capacitive MEMS inertial sensor) measurement systems, particularly in applications demanding high precision, low noise, and wide dynamic range. Its core value lies in directly and high fidelity converting the weak charge signal output by the sensor into a digital frequency signal. The following introduces the typical applications and advantages of the charge integrator I/F module in inertial sensor systems:
Capacitive MEMS Accelerometer/Gyroscope Signal Readout
The charge integrator I/F module is used to detect small capacitance changes in the output signals of MEMS inertial sensors (accelerometers, gyroscopes). It directly measures charge and is extremely sensitive to charge changes at the fC (flying coulomb) level, capable of detecting extremely small inertial forces. The integration process itself is a low-pass filter, which can effectively suppress high-frequency noise. Using frequency signals as output, it is insensitive to amplitude noise and interference on the transmission path, making it suitable for long-distance transmission or use in noisy environments.
High Precision/Force Balanced(Servo/Force-Feedback) Inertial Sensor
In the highest precision inertial sensors, such as navigation grade MEMS or quartz beam accelerometers, a force balance closed-loop working mode is commonly adopted. The detected small displacement (sensed through capacitance/charge changes) is converted into feedback force, which is applied back to the mass block to keep it near zero. In this design process, the I/F module plays a dual role as the driver source for front-end detection and feedback DAC. Achieved ultra-high precision, stability, and precise force control. At the same time, it simplifies the closed-loop control architecture, enabling the entire closed-loop system to be efficiently implemented in the charge/frequency/digital domain.
Typical Application Scenarios
l High precision navigation and positioning: high-precision inertial navigation systems and inertial measurement units for aviation, aerospace (satellites, rockets), ships, and land vehicles. The requirements for zero bias stability, noise, and scale factor linearity are extremely high.
l Earthquake monitoring and geophysical exploration require the measurement of extremely weak ground vibrations (as low as μg acceleration), with strict requirements for low-frequency noise and dynamic range.
l Industrial automation and robotics: precision motion control, platform stability, vibration monitoring.
l Structural health monitoring: detection of small deformations and vibrations in large buildings, bridges, and dams.
l Automotive electronics: advanced driving assistance systems, high-performance MEMS IMUs required for autonomous driving.
I/F Conversion Module Products
As an inertial sensor designer and manufacturer, Micro-Magic Inc has designed and manufactured a series of high-precision inertial sensor products, such as quartz flexible accelerometers, fiber optic gyroscopes, IMUs, INS, North Seeker, and inclinometers. At the same time, AVI series charge integration I/F (V/F) module products have also been developed in conjunction with it.
AVI-F AVI-E AVI-B Performance Index
|
Specification |
AVI-B |
Unit |
||
|
Maximum output frequency |
256 |
512 |
512 |
kHz |
|
Zero position F0 |
10 |
20 |
100 |
nA |
|
Zero stability |
5 |
5 |
10 |
ppm |
|
Scale factor temperature coefficient |
1 |
0.5 |
1 |
ppm/℃ |
|
Scale factor asymmetry |
10 |
30 |
30 |
ppm |
|
Scale factor comprehensive nonlinearity |
15 |
30 |
30 |
ppm |
|
Small signal error |
0.2 |
0.5 |
0.5 |
Hz |
Conclusion
The charge integrator I/F module is one of the key technologies for achieving high-performance and high-precision signal readout of capacitive inertial sensors, especially MEMS accelerometers and gyroscopes. It is an essential core component in advanced inertial measurement applications that require extremely low noise, ultra-high linearity, wide dynamic range, and digital closed-loop control, providing a critical signal chain solution for high-end inertial sensors at the navigation, tactical, and even some industrial levels. With the advancement of MEMS technology and readout circuit technology, readout schemes based on charge integration principle continue to play an important role in the field of high-performance inertial sensors.
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