Reference Signal Circuitry for Source Impedance Measurement
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Solution Overview
Problem
Conventional digital multimeters (DMMs) lack the capability to determine source impedance of a device under test (DUT), which is essential for accurate voltage measurement and can be confused by ghost voltages due to high input impedance, leading to incorrect readings.
Innovation Solution
An electrical parameter measurement device with reference signal circuitry that generates an AC reference voltage, detects signals at both the voltage test input and common input terminals, and processes these signals to determine impedance and other electrical characteristics, including ghost voltage detection and inductance/capacitance values, using a common mode reference voltage source and processing circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DMMs use high input impedance for voltage measurement, then measurement safety and minimal circuit loading are improved, but the ability to distinguish real voltage from ghost voltage deteriorates
Solution Approach 1:
The patent introduces a reference signal generator as an intermediary that injects a known test signal into the common input terminal. This mediator allows the system to characterize the input impedance and detect ghost voltages by comparing the expected reference signal with the actual measured signal, thereby resolving the contradiction between high input impedance safety and measurement accuracy.
2Device complexity
If conventional DMMs lack source impedance measurement capability, then device simplicity is maintained, but the ability to perform accurate voltage measurements and detect ghost voltages deteriorates
Solution Approach 1:
The patent implements multi-functionality by enabling the DMM to perform not only standard voltage measurements but also source impedance measurement and ghost voltage detection using the same basic circuitry. The reference signal generator and processing circuitry allow a single device to execute multiple measurement functions, resolving the contradiction between device simplicity and measurement precision.
3Device complexity
If DMMs use conventional measurement circuitry without reference signal injection, then device complexity is reduced, but the capability to determine source impedance and detect ghost voltages deteriorates
Solution Approach 1:
The patent applies preliminary action by injecting a known reference signal into the common input terminal before performing the actual voltage measurement. This preliminary signal injection allows the processing circuitry to pre-characterize the input impedance and identify ghost voltage conditions, making the subsequent voltage measurement more accurate and reliable without significantly increasing overall device complexity.
Data Source
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AI summary
Systems and methods provide measurement of one or more electrical parameters (e.g., impedance) of a device under test (DUT) using an electrical parameter measurement device (e.g., multimeter, oscilloscope) that includes reference signal circuitry that generates, detects, and processes common mode reference signals. A measurement device may include a known common mode AC reference voltage source coupled to a common input terminal. During measurement of a DUT, circuitry may detect a signal at a voltage test input terminal and a signal at the common input terminal. The circuitry may process the first and second signals to determine one or more electrical parameters of the DUT, which one or more electrical parameters may be used to implement one or more features. The determined electrical parameters may be presented to an operator via a visual indicator device and/or may be communicated to an external device via a wired and/or wireless communications interface.