Capacitance Measurement Circuit with Periodic Refinement
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Solution Overview
Problem
Existing measuring devices for determining capacitance in pressure measurement face limitations in resolution due to sampling frequency and measurement time, leading to increased power consumption and measurement errors when trying to enhance resolution.
Innovation Solution
A measuring device with a circuit that uses a series of delay elements and comparators, activated only at the end of a measurement cycle, and a clock-synchronous measuring oscillator to reduce energy consumption and improve accuracy, allowing for increased resolution without extending measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sampling frequency is increased to achieve higher resolution, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The refinement circuit is activated periodically only during the final portion of the measurement cycle rather than continuously. Specifically, the circuit is enabled when the measurement time counter reaches a threshold value (e.g., 4 ms in a 5 ms cycle) and disabled after completing the refinement operation, creating a pulsed activation pattern that reduces average power consumption while maintaining measurement precision.
Solution Approach 2:
The measurement system dynamically adjusts the operational state of the refinement circuit based on the measurement timeline. The circuit transitions from an inactive state to an active state at a predetermined time point during the measurement cycle, allowing the system to optimize between power consumption and measurement accuracy by being active only when necessary for the final high-precision measurement phase.
2Measurement precision
If the measurement time is extended to achieve higher resolution, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The refinement circuit operates periodically during the measurement cycle, activating only during the final high-precision phase rather than throughout the entire measurement duration. This allows the system to maintain high resolution requirements while keeping the majority of the measurement cycle dedicated to faster, lower-power preliminary measurement phases.
3Measurement precision
If delay elements and comparators are continuously activated to increase resolution, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The delay elements and comparators within the refinement circuit are activated periodically only during the final portion of the measurement cycle. The circuit receives control signals that enable it to perform refinement operations on the final measurement value while remaining inactive during other phases, thereby significantly reducing the average power consumption of these high-power components.
Solution Approach 2:
The refinement circuit dynamically changes its operational state based on the measurement timeline, transitioning from a low-power inactive state to a high-performance active state only when needed for the final high-precision measurement phase. This dynamic control allows the delay elements and comparators to operate at full capability when required while minimizing energy consumption during the majority of the measurement cycle.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The measuring device has a clock oscillator which oscillates in a sampling frequency. A measuring oscillator (3) oscillates depending on the swinging of a measuring capacitor (CM) in a measurement frequency. An edge counter counts the number of clock oscillations for a certain number of measuring vibrations. A measurement circuit is started by a measuring edge of a last sampled measured oscillation, and is stopped by an equally oriented and immediately following edge of a subsequent clock oscillation. An independent claim is included for a method for determining measuring-capacitance.