Precision Voltage Source Research Articles

Characterization of a precision modular sinewave generator

At the Czech Metrology Institute (CMI) we have developed a precision modular sinewave generator for impedance ratio bridges. The generator was developed to improve previously available designs regarding amplitude and phase accuracy, linearity, absolute stability, stability of the ratio between two outputs and harmonic distortion. It generates up to 7 Vrms in a frequency range from 1 mHz up to 20 kHz, extendable to 100 kHz with small changes to the filters. The amplitude resolution is better than 0.01 μV V−1 of full scale with an output voltage stability of 0.05 μV V−1/30 min and a stability for the ratio between two outputs of 0.02 × 10−6 over several hours. The generator can be powered from internal batteries and is controlled via optically isolated connections. The internal clock and voltage references can be replaced by external ones, optically coupled in the case of the clock. In this paper, we discuss experimental results obtained with the generator used as a signal source in digital impedance bridges with relative combined uncertainties from 10–5 down to 10–8. The generators have been used in a bridge to drive a quantum Hall resistor in the AC regime. The use of a generator with an AC quantum voltmeter will also be discussed. The generator is not only applicable in the field of AC impedance metrology but also for on-site comparisons of AC quantum voltage standards or, in general, where there is a need for precision voltage sources.

Instruments for automatic test

Every engineer has used test instruments. From the humble handheld multimeter to the most complex protocol analyzer, test instruments are used by engineers in the field and the design lab, in repair shops and environmental chambers, in research, and in quality assurance (QA). Visit any electronics lab and you'll likely find arrays of instruments, stacked three high on lab benches, all of them familiar tools from familiar manufacturers. Walk down the hall from the lab to the test floor at a semiconductor manufacturer, a contract PC manufacturer, or even a military repair depot, and the familiarity falls away. Instead of multimeters, oscilloscopes, and precision voltage sources, you will find systems full of specialized instrumentation, often made by unfamiliar companies. The corridor between the design lab and the test floor seems to connect two different worlds. This discontinuity is not because the laws of electronics are different in the two worlds; it’s caused by the constraints bounding the test engineer. These constraints have required the creation of a different breed of test instrument, called automatic test equipment (ATE). The line between lab equipment and ATE isn't a sharp one but it's sometimes sharp enough to necessitate entirely different instrument designs. This article explores some of the general themes driving production instrument designs and gives some examples of the impact of production requirements on ATE design. The challenge for ATE designers is to cover all the boundary conditions while making sure that performance is always valued and cost effective.

AC Josephson voltage standard error measurements and analysis

The Josephson arbitrary waveform synthesizer can be used as a precision voltage source for both AC and DC signals. Recent improvements in circuit designs have resulted in output voltages greater than 100 mV rms for AC metrology measurements in the frequency range from 1 to 50 kHz. In this paper, we present measurements of several significant error sources that must be considered in order to create an intrinsic AC voltage standard at these frequencies. These results and the corresponding theoretical analysis allow us to move toward creating a practical AC Josephson voltage standard.

A low-cost GPIB programmable precision voltage source

We have developed a simple, low-cost, GPIB programmable precision voltage source for laboratory use with two outputs in the range [0,−5]V and [0,+5]V. The original goal was to allow the interfacing to personal computer of older high-voltage sources that can be remotely driven by an analog signal. This voltage source can be more generally used whenever a GPIB programmable low-power precision voltage source is needed.

Sub‐kHz precision voltage‐controlled‐oscillator system for laser frequency control: An application in atom optics

A system design is presented which allows a voltage controlled oscillator (VCO) to be tuned to an arbitrary frequency between 78 and 94 MHz with an accuracy better than 1 kHz (10 ppm). The temperature coefficient is on the order of 1 kHz/K, giving a long‐term stability better than 1 kHz in a controlled environment. The slew rate for frequency switching is ≊10 MHz in 50 μs. The system comprises a computer‐controlled precision voltage source, a spline interpolation of the voltage versus frequency characteristic, and good isolation of the VCO electronics from the subsequent circuitry. It provides an extremely low‐cost alternative to frequency synthesisers. In our application involving the launching of slow atoms at a target, we can achieve atomic velocities as low as 10 cm/s with 1 cm/s precision.

An ADC test system based on the Macintosh computer

An ADC test system based on UA1 Macintosh development system is described. The test system includes a CAMAC, 12 bit, 1 /spl mu/s ADC module, an I/O Register, an HP pulse generator, a NIM dual timer and a GPIB programmable Keithley 237 high precision voltage source. The first test program was written in Fortran which gave the test results and histograms on the screen. A new Lab-VIEW 2 test program is also described. An upgrade of the test system and the CAMAC control to VME ADC is now in progress.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Eight‐Parameter PC‐AT based flow cytometric data system

An 8-parameter flow cytometric data system is described using an IBM-AT compatible personal computer (PC) and a commercial analog to digital conversion (ADC) board. A dedicated pulse processing interface adapts the flow cytometric pulses to the ADC board and controls the number of parameters to be taken up and the trigger conditions. The trigger thresholds are automatically held at a level immediately above the noise level. For the timing of kinetic measurements a linear voltage ramp of adjustable rise time is available. A built-in precision voltage source can be used for an overall calibration. The data system is operated by software written in assembly language. Data may be collected and processed in 1-8-parameter listmode or 1-3-parameter histogram mode. Functions are available for graphical color displays, numerical integration, multiparameter gating, and printing.

Microwave phenomena in thin- film Josephson junctions coupled to a contiguous microstrip resonator

A half-wavelength microstrip resonator has been used to couple microwave radiation between Josephson junctions and an external 50 Ω transmission line, and various microwave properties of these resonator-coupled junction devices have been studied. The advantages of these devices in applications including coherent radiation emission, 2e/h precision voltage sources, and parametric plasma-related effects are described.

A High Speed Technique for Testing Spacecraft Telemetry Systems

Present methods of automatically testing spacecraft PCM telemetry systems utilize a one or two channel decoding scheme in which channel inputs are programmed from a precision voltage source and the PCM output from each channel under test is observed or compared one data channel at a time to a reference word value. This method has the disadvantages of being time consuming, placing extreme requirements upon the precision voltage source in voltage accuracy and ambient noise, and failing to simulate realistic data configurations in the output serial PCM wavetrain. A high speed technique which overcomes these advantages establishes a reference PCM data train from a reference PCM system which is electrically identical to the PCM system under test and is synchronized bit by bit so that a real time comparison to the reference PCM data train may be made. Word identification is maintained to identify channel location of errors in the system under test. By this method eleven point channel accuracy testing of a Gemini type format of 240 channels can be reduced from the present 90 minutes to 27 seconds. Since both PCM data trains are synchronized sampling times of the A/D converters are precisely at the same point in time and since corresponding channels are driven from the same source an inaccuracy due to voltage programming or test set ambient noise on the data input line is nullified.