Capacitance Ratio Measurement via DC Signal Comparison
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Solution Overview
Problem
Existing attenuation measurement devices face challenges in efficiently and robustly calibrating capacitance ratios, particularly due to variations in capacitance types and process variations in integrated circuit technology.
Innovation Solution
An attenuation measurement device comprising a detector unit with a coupling capacitance and an input capacitance, a test unit, a calibration unit, and a control unit that uses a test signal and a calibration signal to derive capacitance-indicative information, such as a capacitance ratio or attenuation, through DC measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional AC transfer and nulling techniques are used to determine capacitance ratios, then measurement can be achieved, but measurement precision deteriorates due to process variations and different capacitor types
Solution Approach 1:
The patent changes the measurement parameter from AC domain to DC domain. By measuring DC voltage levels at the detector output for both the test signal path and calibration signal path, the method eliminates frequency-dependent effects and reduces sensitivity to process variations in capacitor values, thereby improving measurement precision and reliability
Solution Approach 2:
The patent replaces the conventional AC-based electrical measurement system with a DC-based measurement system. This substitution uses DC voltage comparisons instead of AC transfer functions, simplifying the measurement process and reducing the impact of capacitor type differences and process variations on measurement accuracy
2Device complexity
If simple linear AC transfer techniques are used, then device complexity is reduced, but measurement precision deteriorates due to inability to compensate for capacitor variations
Solution Approach 1:
The measurement system uses itself to calibrate and verify the capacitance ratio. By incorporating a calibration signal path with known capacitor values and comparing its DC output to the test signal path DC output, the system performs self-verification and self-calibration, achieving high precision without requiring complex external calibration equipment
Solution Approach 2:
The patent transitions from AC parameter measurements to DC parameter measurements. This parameter change enables the use of simple DC voltage comparators instead of complex AC measurement equipment, reducing device complexity while improving precision through direct voltage level comparisons that are less sensitive to component variations
Data Source
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AI summary
It is described an attenuation measurement device (100), comprising: i) a detector unit (110) having a coupling capacitance (120), and an input capacitance (130), wherein the detector unit (110) is configured to produce a detector output signal (112a,b) in reply to an input signal received at the coupling capacitance (120) and/or at the input capacitance (130); ii) a test unit (140), coupled to the detector unit (110), and configured to provide a test signal (141) with at least one known signal property as a first input signal to the coupling capacitance (120); iii) a calibration unit (150), coupled to the detector unit (110), and configured to provide a calibration signal (151) as a second input signal to the input capacitance (130); and iv) a control unit configured to a) determine a first detector output signal (112a) produced by the detector unit (110) in response to the test signal (141), b) identify a specific calibration signal (151) that yields a second detector output signal (112b) that is comparable to the first detector output signal (112a), and c) derive a capacitance-indicative information based on the identified specific calibration signal (151).