Injection-Locked Sensor Interface for High-Leakage Environments
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Solution Overview
Problem
Existing sensor interfaces in hostile environments, such as extreme temperatures and high radiation, face challenges due to parameter variations that lead to increased current leakage and potential failures, requiring a more robust and precise solution.
Innovation Solution
An interface circuit utilizing injection-locked oscillators with phase-shifting capabilities, coupled with a calibration circuit and output circuit to generate a digital signal based on phase differences, effectively addressing parameter variations by adjusting free-running oscillation frequencies and providing robustness against environmental changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensors are placed in hostile environments (extreme temperatures, high radiation), then sensing capability is improved, but current leakage increases exponentially leading to circuit failure
Solution Approach 1:
The patent replaces traditional voltage-based sensing circuits with a frequency-based oscillator system. The sensor signal modulates the oscillation frequency rather than relying on voltage levels, making the system immune to temperature-induced current leakage and power supply variations that plague conventional analog circuits in hostile environments.
Solution Approach 2:
The invention transforms the sensor output from a voltage signal susceptible to leakage into a frequency-modulated oscillation signal. By changing the operating parameter from voltage to frequency, the system achieves stability against temperature and radiation effects that cause exponential current leakage in traditional circuits.
2Measurement precision
If traditional sensor interfaces are used in hostile environments, then device simplicity is maintained, but measurement precision deteriorates due to parameter variations
Solution Approach 1:
The patent introduces injection-locked oscillators as intermediary devices between the sensor and the digital output. These oscillators translate the sensor's frequency-modulated signal into a phase-shifted output that can be easily measured, acting as a buffer that isolates the sensitive sensor from environmental variations while maintaining signal integrity.
Solution Approach 2:
The system uses over-determined measurement by comparing multiple oscillator outputs and using digital signal processing to extract the sensor signal. This excessive action in terms of computational processing compensates for the added hardware complexity, achieving high precision through redundancy and error correction.
3Reliability
If robust sensor interfaces are designed for hostile environments, then reliability is improved, but power consumption increases
Solution Approach 1:
The patent employs periodic oscillation rather than continuous analog signal processing. The injection-locked oscillators operate in discrete cycles, consuming power only during active oscillation periods rather than continuously, thereby reducing average power consumption while maintaining reliable operation in hostile environments through the inherent stability of oscillatory systems.
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
The solution enhances sensor interface precision and robustness in hostile environments by converting sensor signals into phase shifts, reducing sensitivity to temperature and power variations, and achieving low power consumption and high-quality digital output signals.
Implementation Method 1
a first injection-locked oscillator having: a first input coupled to a sensor, a free-running oscillation frequency of the first injection-locked oscillator being controlled by a signal from the sensor; and a second input coupled to receive a synchronization signal at a reference frequency, the first injection-locked oscillator being adapted to generate an output signal at said reference frequency, the output signal being phase shifted with respect to the synchronization signal as a function of the signal from the sensor
Data Source
Figure 1~3B
Figure 4~5
Figure 6~7B
AI summary
The invention concerns an interface circuit for a sensor comprising: a first injection-locked oscillator (104) having: a first input coupled to a sensor (102), a free-running oscillation frequency (f0) of the first injection-locked oscillator (104) being controlled by a signal from the sensor (102); and a second input coupled to receive a synchronization signal (VSYNC) at a reference frequency (fSYNC), the first injection-locked oscillator being adapted to generate an output signal (VILO1) at said reference frequency, the output signal being phase shifted with respect to the synchronization signal (VSYNC) as a function of the signal from the sensor.