Tunkia Nanovoltmeter Calibration Solution

1. What is a Nanovoltmeter?

A nanovoltmeter is a specialized instrument for measuring low DC voltage, maintaining high sensitivity and accuracy even at the nV level. Compared to conventional digital voltmeters, nanovoltmeters provide precise ultra-low voltage measurements with faster measurement speed, high input resistance, and significantly improved noise performance. They are more suitable for stable low-noise voltage measurements and reliable, repeatable calibration of low-resistance materials and devices.

2. Typical Applications of Nanovoltmeters

Given the flexible and high-performance low-level measurement capabilities of nanovoltmeters, they are widely used in precise low-voltage output measurements of non-electrical precision sensors or sensitive components like pressure, temperature, and vibration sensors, as well as in precise low-voltage control signal measurements in aerospace and military equipment, and the calibration of precision low-voltage sources. Due to their ease of use, nanovoltmeters have gradually replaced potentiometers.

2.1 Hall Effect Measurement

Hall effect measurements are extremely useful for material characterization in semiconductor manufacturing. However, the Hall voltage is generally very small (millivolts or even lower), so nanovoltmeters are typically used for these measurements.

2.2 Low Resistance Measurement

For low resistance measurements, the four-wire (Kelvin) connection method is generally used. The current reversal method is employed to cancel out the thermoelectric effect. In practice, a current source is paired with a nanovoltmeter for low resistance measurement.

2.3 Superconductor Resistance Measurement

Superconducting materials are generally tested under low current densities (milliamps to tens of amps). Since the tests involve small test currents and extremely low resistance, nanovoltmeters are used for measurements.

3. Calibration Items and Methods of Nanovoltmeters

Calibration Items: The calibration specification for nanovoltmeters primarily targets the DC voltage measurement function of the device.

Calibration Methods: Quantum Voltage Method, Standard Source Method, Standard Voltage Divider Method, Current-Voltage Conversion Method. Different calibration methods use different standards to compare with the nanovoltmeter under test to determine the measured error. The specific comparisons are as follows:

4. Comparison of Calibration Methods of Nanovoltmeters

The calibration of a nanovoltmeter can be done using different methods depending on the calibration needs. The Quantum Voltage Method offers the highest accuracy, but the quantum voltage reference requires complex storage conditions and usage methods, making calibration possible only in national metrology institutes. The Standard Source Method, an original solution by Tunkia, offers the lowest cost, high accuracy, and the most convenient operation compared to other methods.

5. Tunkia’s Nanovoltmeters Calibration Solution

Tunkia's nanovoltmeter calibration solution includes the TH1200 Nanovoltmeter Calibration Device, TH1950 High-Precision Multifunction Calibrator, TH0320 Reference Resistance Standard, and TH1000 Ultra-Stable Current Standard. (Some calibration methods may require a high-precision 8.5-digit multimeter.) The calibration operations can be performed according to the calibration items specified in JJF XXXX-202X "Nanovoltmeter Calibration Specification."

5.1 Standard Source Method

• Measurement uncertainty up to 6ppm @10V

• Typical mV output stability up to 1.8nV/min

• Dual channel voltage outputs are connected using low thermal EMF terminals

• Supports automatic zeroing to eliminate errors caused by internal thermal EMF

• Supports automated calibration through host computer software

5.2 Standard Voltage Divider Method

• TH1950 output voltage short-term stability reaches 1.5ppm/min, superior to the relative maximum allowable error absolute value of the nanovoltmeter by 1/10

• TH0320 maximum working voltage and nominal resistance value cover the nanovoltmeter calibration range, with annual stability reaching 5ppm, meeting calibration requirements

• Before calibration, the DC voltage divider composed of standard resistors needs to be calibrated using the bridge method

• Different standard resistors need to be switched according to the test range during the experiment

5.3 Current-Voltage Conversion Method

• TH1000 output current short-term stability reaches 10ppm/min, superior to the relative maximum allowable error absolute value of the nanovoltmeter by 1/10

• TH0320 maximum working voltage and nominal resistance value cover the nanovoltmeter calibration range, with annual stability reaching 5ppm, meeting calibration requirements

• Before calibration, the DC voltage divider composed of standard resistors needs to be calibrated using the bridge method.

• Different standard resistors need to be switched according to the test range during the experiment