Doppler Sensor Oscillator Layout for Stable Frequency Tuning
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Solution Overview
Problem
Conventional high-frequency oscillator devices for motion and presence sensors face challenges in reproducibly determining oscillation frequency due to manufacturing tolerances, requiring laborious trimming and calibration, and suffer from mutual interference between adjacent sensors, necessitating complex adjustments.
Innovation Solution
The use of a coaxial ceramic resonator with a microstrip line configuration, eliminating the need for coupling capacitors and allowing frequency variation through microstrip line length adjustments, enables reproducible and interference-free operation by varying the length of the matching line between the ceramic resonator and the bipolar transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coupling capacitors are used to connect the resonator to the bipolar transistor, then the oscillator exhibits reliable oscillation behavior, but the oscillation frequency cannot be determined precisely due to component and manufacturing tolerances
Solution Approach 1:
The invention removes the coupling capacitor from the circuit and directly connects the resonator to the bipolar transistor collector. This extraction eliminates the source of frequency uncertainty (capacitor tolerance) while preserving the reliable oscillation behavior through direct coupling.
Solution Approach 2:
The invention changes the local coupling characteristic from capacitive (indirect) to direct conductive coupling. By modifying the local connection quality between resonator and transistor, the frequency determination precision is improved without compromising overall oscillation reliability.
2Measurement precision
If trimming or calibration is performed after manufacturing to achieve precise oscillation frequency, then the oscillation frequency precision is improved, but the production time and costs increase significantly
Solution Approach 1:
The invention performs frequency determination during the manufacturing process itself through direct coupling design, rather than requiring post-manufacturing trimming or calibration. This preliminary action integrates frequency setting into the fabrication process, eliminating additional time-consuming steps.
Solution Approach 2:
The oscillator circuit automatically determines its oscillation frequency through the direct resonator-transistor coupling without requiring external trimming or calibration operations. The system is self-configuring during manufacturing, eliminating the need for manual or automated post-processing adjustments.
3Area of stationary object
If multiple sensors are mounted in a detection area, then the sensor system achieves comprehensive coverage, but mutual interference between neighboring sensors occurs
Solution Approach 1:
The invention enables easy variation of the oscillation frequency parameter by changing the resonator physical dimensions (length, area). This allows each sensor in the detection area to operate at a unique frequency, eliminating mutual interference while maintaining comprehensive coverage.
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
This solution simplifies large-scale production, increases reproducibility of vibration behavior, and reduces component-related tolerance effects, eliminating the need for individual adjustments and minimizing mutual interference between adjacent sensors.
Implementation Method 1
a resonator section (10) mounted on a printed circuit board and comprising a resonator means (12) and a matching line (14) in the form of a microstrip line
Implementation Method 2
such sensors typically operating according to the Doppler principle
Data Source
Figure 1~3
Figure 4
AI summary
The invention relates to a high-frequency oscillator device with a resonator section (10) provided on a printed circuit board, comprising a bipolar transistor (18) and ceramic resonator means (12), which is configured for oscillator operation of the oscillator device at a fixed frequency, wherein the resonator means forming a first end of the resonator section on the printed circuit board are connected to the base (B) of the bipolar transistor via an matching line implemented as a first microstrip line (14), and the bipolar transistor is connected such that, in oscillator operation, a wave maximum of a superimposed forward (24) and reflected (26) standing wave along the resonator section is present at the base.