AccuBridge® 6020Q

Self-Calibration Quantum Hall Ratio/Resistance Bridge

  • Quantum Hall Applications Including Gallium Arsenide and Graphene Sample Measurements
  • Vcr, Vxx, and Vxy Measurements
  • Self-Calibration of the Binary Wound Current Comparator (27-bit) Plus Nanovolt Detector Reading
  • Current Range from 1 μA to 200 mA
  • Ratio 0 to 14:1
  • Resistance Range 0.1 Ω to 100 kΩ
  • 7″ Touch Screen with USB
  • Best Accuracy < 15 ppb
Features & Benefits

As the leading provider of top-notch resistance measuring equipment, Measurements International (MI) proudly presents the AccuBridge® 6020Q Automated Resistance Bridge. Known for its exceptional speed, precision, and measurement accuracy, the 6020Q is the preferred choice of National Measurement Institutes (NMIs) across the world. Its innovative design and user-friendly operation make it an ideal solution for stand-alone resistor calibrations and primary resistance measurements. With its unparalleled performance, the 6020Q is sure to raise the bar in the world of resistance metrology.

Feature Benefit
DCCT based. Provides excellent stability and range linearity.
Vcr, Vxx and Vxy measurements. Supports dissipation and contact resistance checks.
< 15 parts in 10-9 ratio accuracy. Allows sub-ppm high-stability measurements.
Ratio 0 to 14:1 Compatible with both gallium arsenide and graphene sample measurements.
National lab continuity. The only commercially available QHR resistance bridge used in primary or national laboratories worldwide.
Full DCC resistance range. 0.1 Ω to 100 kΩ.
Stable low currents. 1 μA to 200 mA ensures ultra low noise measurements.

QHR Measurements

As a stand-alone device, the 6020Q is capable of performing the sweep check, contact resistance, longitudinal potential difference (dissipation) and hall resistance measurements on the Quantum Hall Resistance (QHR) sample. You can select menu-driven functions using the front panel display or over IEEE-488. Also, you can use the 6020Q as a high accuracy DC resistance ratio bridge for calibrating resistors using either an 1 Ω or 10 kΩ standard resistors. For laboratories without a QHR system, the 6020Q can be used to build up from the 1 Ω or down from the 10 kΩ.

Figure 4 – Sweep Check Measurements

The 6020Q performs the field sweep check measurement (see figure 4) by feeding a current, into the source and drain of the sample, and then reversing it. This enables the measurement of potential differences between various points on the sample. These potential differences can be measured at Hall resistances Vxy (1-2) or Vxy (3-4) and the longitudinal resistance Vxx (1-3) and Vxx (2-4) on the sample. Vxy (1-2) and Vxy (3-4) should be in close agreement with each other, as should Vxx (1-3) and Vxx (2-4).

The 6020Q’s microvolt detector makes contact resistance measurements. It is important to measure the contact resistance each time the QHR device is cycled to room temperature and re-cooled as large contact resistances can lead to errors in the QHR measurement. The 6020Q uses a three-probe measurement on each of the contacts in turn to measure the contact resistance. The contact resistance is equal to Vcr/I = resistance of wire + resistance of contact + resistance of 2-DEG.

For an accurate transfer of the QHR value, the longitudinal potential difference must be measured. You can do this by measuring between Vxx (1-3) and Vxx (2-4) using the 6020Q’s Vxx nanovolt mode. Take this measurement to verify that there is no dissipation in the 2-DEG. When the 2-DEG is quantized, Vxx should go to 0 and should be < 2 × 10-8 of Vxy.

For traceable measurements, use the keypad on the touch screen to enter the QHR value and related uncertainty in the resistor ID standards file and the 1000 Ω transfer resistor into the measurand (unknown) ID file. Enter standard resistors such as the 1 Ω or 10 kΩ into the standards file after they have been calibrated. Enter resistors to be calibrated into the measurand (Rx) or unknown file. Using the keypad, enter measurement functions such as current through the unknown resistor, settle time, number of measurements, and number of statistics into the Programs file.

Example (for stated specifications)
Maximum Current Reversal Rate = 12 seconds
Maximum Measurement Setting = 50 Measurements
Maximum Statistical Settings = 40 Measurements

The 6020Q is compatible with all the QHR systems, both the 6800A and 6800B software, as well as both the 4220 and 4210 Matrix Scanners.

When performing resistance measurements, the 6020Q’s low-noise, the touch screen display is interactive with the measurements. You can display data (several measurements at a time), a combination of data and a graph of the measurements, or just the graph. When a reading is complete, the average value and uncertainty (based on the number for statistics) are displayed. All uncertainty calculations are 2σ level. For resistance measurements, the Summary screen displays measurement data as well as graphical information for current measurements, which can be viewed anytime in ratio or ohms.


Windows® Based Operating Software

Measurements International’s software features an MI report generation, historical analysis and tracks and corrects for resistor drift rates. Combined with a 9400 Standard Resistor Oil Bath or 9300A Air Bath, alpha and beta calculations can be performed automatically on resistors under test. All data can be exported directly to Excel for creating various test patterns or mainframe applications. Resistor baths (oil or air), instrument controllers, printers, system software, IEEE interface, installation, and training are all available from MI.

Main Manual Screen
Main Manual Screen

Resistor ID Listing
Resistor ID Listing

Program Selection & Creation
Program Selection & Creation

Rack & Rack Settings
Rack & Rack Settings

Measurement Options
Measurement Options

History Information
History Information


Channel Extension

By using combinations of up to four matrix scanners, you can increase the number of input channels to almost any number from 10 to 40. Our Automated Low Thermal Matrix Scanners include the 4210A and 4210B with ten input and two output channels; 4216A, 4216B with 16 input and two output channels; and 4220A and 4220B with 20 input and two output channels. Our A-series of matrix scanners have tellurium copper terminals on their inputs and outputs while our B-series units have four-wire Teflon cable on their inputs and outputs.

Model 9300 Air Bath

9300 Air Bath
The model 9300 series Air Baths are designed as a convenient and inexpensive way to maintain the temperature of air resistors in your calibration laboratory. It is large enough to house several standard air resistors and features an adjustable shelf to permit easy access to the standards. The shelves are easily removable to place a single ESI type SR104 standard in the bath. The bath is small and rugged and may be moved about easily.

Model 9300A Temperature Controlled Chamber with IEEE-488

The 6020Q is also ideal for verifying the temperature and power coefficient of resistors or shunts using the MI 9300A Air Bath. Up to four SR104’s or a combination thereof can be installed in the bath, two shelves are provided. The bath can be supplied without IEEE and with IEEE. The IEEE drivers for this bath are built into the software for automated measurements and calculations of alpha, beta coefficients and resistor values. A Hi/Lo temperature protection circuit is built into the bath to protect your resistors.

Model 9400 Oil Bath with IEEE-488

9400 Oil Bath

We designed our model 9400 Standard Resistor Oil Bath based on years of customer feedback on existing resistor oil baths. You control this bath through a touch screen interface. Due to its low electrical noise, the quiet 9400 can be used with the Cryogenic Current Comparator (CCC) and QHR standard. Depending on the number of resistors in the bath, the stirrer motor speed can be changed. The IEEE drivers for this bath are built into the software for automated measurements and calculations of alpha and beta coefficients and resistor values.

Model 9331 & 9331R Series Air Resistors

9331R/1K Standard Reference Resistor

9331/1.9 Standard Resistor
Our high accuracy working standard air resistors are used for precision on-site resistance calibrations for values from 1 mΩ to 100 MΩ. Our 9331’s are small, light, and rugged resistance standards that do not require a temperature-controlled oil or air bath for their specification range. The stability and temperature coefficients of the 9331’s make them ideal for easy transport and operation in any working environment within the range of 18 °C to 28 °C.

Connections to the model 9331R are made with tellurium copper 5-way binding posts for values to 10 MΩ. A separate ground terminal is included for guarding and the case is hermetically sealed to keep moisture out. The model 9331 ranges from 0.001 Ω to 10 MΩ.

Model 9210 Series Standard Oil Resistors

9210B - Measurements International

9210A/1 Primary One Ohm Standard with carrying case

Oil resistors provide better stability and temperature coefficients over air resistors and provide the highest precision and stability in resistance measurements. Our standard oil resistors include the 9210A Primary 1 Ω, 9210A Primary 0.1 Ω, and 9210B series from 10 Ω to 100 kΩ. The 9210A 1 Ω and 9210A 0.1 Ω resistors have a negligible pressure coefficient.

Either Rs or Rx can be selected as the standard. 6020Q uncertainties
in the bridge and software are specified at the 2σ level (95 %) this includes all secondary specifications such as linearity and noise with a ± 2 °C temperature variance.
0.1 Ω to 100 kΩ
Rx Ratio & Accuracy (ppm)*
1:1 10:1 14:1
0.1 Ω < 0.02
1 Ω < 0.015 < 0.015 < 0.015
10 Ω < 0.015 < 0.015 < 0.015
100 Ω < 0.015 < 0.015 < 0.015
1 kΩ < 0.015 < 0.015 < 0.015
10 kΩ < 0.02 < 0.015
100 kΩ < 0.05

*As a ratio device, the accuracy specifications can be improved upon based on your standards and environmental conditions.

Measurement Mode 4-wire
Linearity < 0.005 x 10-6 of full-scale
Operating Conditions 10 °C to 35 °C, 10 % to 90 % RH non-condensing
Test Current Range 1 μA to 200 mA
Test Current Resolution 18-bit
Interface IEEE-488
Display Touch-screen display (no external keyboard), resolution 0.001 x 10-6

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