During electronic circuit design and testing, measurementresistanceIt is a basic and important job. Especially in differential circuits, accurate resistance measurement is critical to ensure circuit performance and stability. Differential circuits are widely used in analog signal amplification, data acquisition and other fields because of their good anti-interference ability and high-precision signal processing characteristics. So, how to effectively measure resistance in differential circuits? This article will introduce in detail the methods and steps for measuring resistance in differential circuits to help readers master relevant skills.
1. Understand the basic structure of differential circuitsA differential circuit usually consists of two symmetrical input terminals, which can amplify the difference of input signals and suppress common-mode signals. When measuring resistance, you must first determine where the resistance is located, whether it is the input end, feedback loop, or output end. The resistance measurement methods at different locations are slightly different. Understanding the circuit structure can help choose an appropriate measurement solution.2. Precautions when using a multimeter to measure resistanceThe most commonly used measuring tool is the digital multimeter. The power supply should be disconnected during measurement to avoid the influence of other components in the circuit on the measurement results. Especially in differential circuits, resistors may be connected in parallel with other components, causing deviations in the measured values. It is recommended to disconnect the connecting wires at both ends of the resistor first and measure the resistance value separately.3. Differential measurement method improves measurement accuracyUsing differential measurement, which simultaneously measures the voltage and current between two relevant points, the resistance value is calculated using Ohm's law. This method is suitable for situations where the circuit cannot be powered off or the resistor cannot be removed. Connect the voltmeter and ammeter, record the data and then calculate the resistance, which can effectively eliminate the influence of other components.4. Use an oscilloscope to observe the voltage waveformAn oscilloscope can help observe the voltage waveform across a resistor in a differential circuit, especially in a dynamic signal environment. By measuring voltage changes and corresponding current changes, the resistance value is indirectly calculated. This method is suitable for studying the performance of resistors at different frequencies and analyzing circuit performance.5. Use a bridge measurement circuitBridge measuring circuits such as the Wheatstone bridge are a classic method of measuring precision resistance. Connect the measured resistance to the bridge, balance the bridge by adjusting the known resistance, and calculate the unknown resistance value. This method has high accuracy and is suitable for critical resistance measurements in differential circuits.6. Measurement using constant current sourceA known constant current is injected into the circuit, and the resistance value is calculated using Ohm's law by measuring the voltage across the resistor. The constant current source ensures stable current and avoids measurement errors caused by current changes. This method is suitable for differential circuits containing nonlinear components.7. Pay attention to the impact of environmental factors on measurementEnvironmental factors such as temperature and humidity can affect resistance values and measurement accuracy. The environment should be kept stable during measurement to avoid external interference. For high-precision resistance measurement, it is recommended to perform it in a constant temperature and humidity environment.8. Calibrate measuring instruments to ensure accuracyRegularly calibrate measuring equipment such as multimeters and oscilloscopes to ensure accurate and reliable measurement results. Standard resistors can be used as a reference during calibration to improve measurement accuracy.：There are various methods for measuring resistance in differential circuits, and choosing the appropriate method depends on the circuit structure, measurement conditions, and required accuracy. Basic multimeter measurements are suitable for simple scenarios, and differential measurement methods and bridge measurement methods are suitable for high-precision requirements. The application of oscilloscopes and constant current sources provides convenience for measurements in dynamic and special environments. By rationally selecting measurement methods, paying attention to environmental effects, and calibrating instruments, the accuracy of resistance measurement in differential circuits can be effectively improved and the normal operation and stable performance of the circuit can be ensured.
