JVS1004 Josephson System Controller with the MMWS-75a Frequency Synthesizer


The JVS1004 is an upgrade of the venerable JVS1002 Josephson System Controller.  It includes a new function (Step Mode) that measures the constant voltage step amplitudes at any set point of voltage frequency and power. The result is displayed on a front panel digital meter and can be read by NISTVolt software. When combined with the automated power control of the MMWS-75a Frequency Synthesizer and NISTVolt control software, it can automatically display the frequency and power dependence of the Josephson array constant voltage steps.  This simplifies the complex task of finding the optimum set points for the JJ array chip.  As of October, 2016, the JVS1004 is being used in four standards laboratories.


The step range circuit uses a lock-in amplifier to detect the maximum array sweep current IA for which the array voltage VA at the sweep frequency is below a threshold level on the order of 100 µV.  A feedback circuit continuously adjusts IA to the threshold level.  If the sweep range lies within the range of a step, VA = 0  causing IA to ramp up.  As IA exceeds the step amplitude, the voltage starts hopping between steps, searching for a larger step.  In a few seconds IA settles at the threshold of the maximum step amplitude.

Like the JVS1002, the JVS1004 accepts IEEE488 commands to control and automate a Josephson array voltage standard.  It controls the array bias, monitors up to10 environmental and system parameters, and sets 8 relays to select different system configurations.  It can be combined with the MMWS-75 frequency synthesizer or the GS1002 Gunn Oscillator Power Supply/Modulator to make a convenient 3.5” high rack width instrument.  It is the link between the Josephson array chip, the 75 GHz oscillator, the system voltmeter, and the control computer.  It comes with a special driver that allows it to work with the program NISTVolt, a voltage standard control program included with every JVS1004 purchase. NISTVolt is also available from NIST at no charge. The JVS1004 can also work with user written software   The JVS1004 may be purchased from VMetrix, LLC as a new unit, or your existing JVS1002 can be upgraded and fully tested to JVS1004 specifications for a much lower cost. In the case of the upgrade, the front panel and main circuit board are replaced (



Computer Input

Opto-isolated IEEE488 port.  Factory set address = 20.

Manual Sweep Generator

Frequency  2 - 35 Hz


Amplitude  0 to ± 12 V

Coarse DC Offset ± 12 V

Fine DC Offset ± 40 mV

DAC Bias Control

± 12 V    0.28 mV LSB

Test Loads

10 - Short - Open     Internal and External

Current Monitor

BNC Output   1 V = 100 μA

Voltage Monitor

BNC Output    1X dc or 100X ac Gain

Switch Module

Auto Switching of Array, DVM, DUT Connections


Internal DUT Reversing Switch  ± 20 nV offset

Step Amplitude Measurement

Digital Readout in microamperes

System Parameter Monitors

DUT Voltage


Josephson Array Voltage

Difference Voltage

Array Current

Temperature, Pressure, Humidity, User Options (2)

Auto Switchable Power Outlet

Used to Float DC References under while test

75 GHz On/Off Control

BNC   0 or +15 V

Power Supply

120/220/240  ac 50-60 Hz  20 W


12 x 12 x 3.5 inches , 31 x 31 x 9 cm    6 kg

Cost  2016

$10000 USD new unit or $3500 JVS1002 upgrade