Digital LCR Meter Balancing With Leakage Impedance Compensation
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Solution Overview
Problem
LCR meters face inaccuracies due to leakage currents and require multiple measurements for balancing, leading to slow measurement times, especially at low and medium frequencies, and are often costly.
Innovation Solution
A digital LCR meter employs a fast-balancing method by separating the measurement of leakage impedance and series impedances during calibration, allowing for single-step balancing and high-accuracy impedance measurement without iterations, utilizing modern processors to maintain speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If modem-type auto-balancing bridge with low-speed integrators is used, then balancing accuracy at high frequencies is improved, but measurement time at low and medium frequencies increases
Solution Approach 1:
The patent pre-calculates and stores balancing voltages in a lookup table before measurements are taken. During actual measurement, the system simply retrieves the pre-computed values based on the measured impedance, eliminating the need for slow iterative balancing calculations during the measurement process itself. This resolves the contradiction by performing the computationally intensive balancing work in advance rather than during measurement.
Solution Approach 2:
The patent separates the measurement process into distinct phases: an initial calibration phase where balancing parameters are pre-computed and stored, and a measurement phase where these pre-computed parameters are applied. This segmentation allows the system to optimize for speed during measurement while maintaining accuracy through the pre-computed balancing parameters.
2Measurement precision
If multiple voltage measurements and iterations are performed for balancing, then measurement accuracy is improved, but measurement speed decreases
Solution Approach 1:
The system pre-calculates balancing voltages and stores them in lookup tables during a calibration phase. During actual measurements, the system retrieves these pre-computed values instantaneously based on the measured impedance, eliminating the need for multiple iterative measurements and calculations during the productivity-critical measurement phase.
Solution Approach 2:
The patent creates a digital copy of the balancing parameters in the form of lookup tables that store pre-computed balancing voltages. Instead of repeatedly performing complex balancing calculations during each measurement, the system copies and applies the appropriate pre-computed values from the lookup table, dramatically improving measurement speed while maintaining accuracy.
3Object-affected harmful factors
If guard method or trans-impedance amplifier is used for leakage compensation, then leakage current suppression is improved, but common voltage suppression at high frequencies deteriorates
Solution Approach 1:
The patent pre-calculates and stores leakage compensation parameters in lookup tables during calibration. During measurement, the system retrieves these pre-computed compensation values and applies them instantaneously, providing effective leakage current suppression without the high-frequency limitations of analog guard methods or trans-impedance amplifiers.
Solution Approach 2:
The patent replaces analog leakage compensation methods (guard methods and trans-impedance amplifiers) with a digital computation approach using lookup tables and microprocessor-based calculations. This substitution eliminates the frequency-dependent limitations of analog circuits while maintaining effective leakage compensation across a wide frequency range.
Data Source
AI summary
An LCR meter with a fast balancing method, with only one necessary measurement of voltages. The LCR meter uses to speed up balancing, separation in time measurement of a device under test (DUT), and other parasitic impedances, including a leakage impedance. The leakage impedance and the other parasitic impedances of a fixture and the LCR meter itself are measured during open/short calibration and saved to memory. The DUT is measured during measurement using already known parasitic impedances. This allows calculating balancing conditions using only one measurement of voltages.