Sensor Device Beat Noise Suppression via Frequency Alignment
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Solution Overview
Problem
Existing composite sensors experience noise interference due to significant current variations in drive circuits, leading to power supply noise and radiation noise that affect other physical quantity sensors, particularly causing beat noise from frequency differences between drive signals and sampling frequencies.
Innovation Solution
A sensor device design that generates an output signal based on a second physical quantity sensor's signal with a frequency n times higher than the drive frequency, where n is an integer equal to or greater than 1, to suppress beat noise, and may include additional components like filters, waveform shaping sections, or level-shift sections to manage noise effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a drive circuit is provided to generate drive signals for driving physical quantity sensors, then the sensors can be driven and function properly, but significant current variation occurs causing power supply noise and radiation noise that affect detection circuits
Solution Approach 1:
The sensor device is divided into separate functional modules: a drive section for generating drive signals, a detection section for processing sensor outputs, and an output section for generating final outputs. This segmentation isolates the noise-generating drive circuit from the sensitive detection circuits, reducing noise interference while maintaining sensor functionality.
Solution Approach 2:
An output section acts as an intermediary between the drive section and the final output. This intermediary processes signals from both the first and second physical quantity sensors, generating output signals based on combined inputs, thereby mediating the interaction between drive signals and sensor outputs while minimizing noise propagation.
2Adaptability or versatility
If the output signal is generated based on the signal from the second physical quantity sensor and a signal with frequency different from the drive frequency, then frequency mixing may occur, but beat noise is generated due to frequency difference between drive signal and sampling frequency
Solution Approach 1:
The output section generates output signals by changing the frequency parameter of the reference signal to be exactly equal to the drive frequency. This parameter adjustment eliminates the frequency difference that causes beat noise, while still allowing flexible output signal generation based on inputs from both physical quantity sensors.
3Device complexity
If multiple physical quantity sensors are housed in the same package or formed on the same substrate, then device integration is achieved, but noise from drive circuits affects other sensors in the composite sensor
Solution Approach 1:
The composite sensor is segmented into distinct functional sections: a drive section containing the drive circuit, and separate detection sections for each physical quantity sensor. This segmentation allows multiple sensors to coexist in the same package while isolating noise sources from sensitive detection areas, maintaining integration benefits while reducing cross-sensor interference.
Solution Approach 2:
The drive circuit is extracted as a separate drive section from the detection circuits. By taking out the noise-generating component and placing it in a dedicated section, the patent reduces noise interference to other sensors in the composite package while maintaining the integrated structure.
Data Source
AI summary
A sensor device includes a first physical quantity sensor, a drive section adapted to generate a drive signal for driving the first physical quantity sensor with a drive frequency, a second physical quantity sensor, and an output section adapted to generate an output signal based on a signal from the second physical quantity sensor and a signal having a frequency n times (n is an integer equal to or greater than 1) as high as the drive frequency.