Measurement and analysis of high-frequency voltage errors in the Josephson arbitrary waveform synthesizer

Abstract

This paper reports on the comparison of two Josephson arbitrary waveform synthesizers for frequencies up to 500 kHz. Both independent pulse-driven Josephson arrays produce a 10 mV RMS sinusoidal voltage. They are alternately connected to an analog-to-digital converter which serves as a transfer standard. The setup is capable to of synthesizing quantum-based waveforms using two different pulse-bias techniques. We use the Zero-Compensation method and a two-pole high-pass filter structure in the pulse-bias configuration of one system (the reference) to minimize the amplitude error for signal frequencies up to 500 kHz. Consequently, we are able to directly detect the high-frequency voltage errors in the other system (the device under test). The setup is used to measure differences between both systems, and the influence of parameter variation on the results with Type A uncertainties of 0.4 µV/V (k = 1) in measurement times of 60 s. We find that the dominant sources of deviations above 10 kHz can be traced to the influence of the output cabling and the pulse bias on the synthesized voltage signal. Our analysis explains the origin and the reduction of these high-frequency voltage errors.

Josephson voltage standards as toolkit for precision metrological applications at PTB

“…the DUT's signal amplitude is dependent on the bias-parameters even when operated on its QLR. The created model described in detail in (Kraus et al 2020) for the feed through error fits well with the experimental results and additional measurements. It is shown that less efficient filtering of the feed through current and/or an outer DCB in conjunction with parasitic inductances in the low-side of the output cabling result in large high-frequency voltage errors.…”

Linearity measurements of critical Johnson noise thermometer components with low-distortion multitones from a Josephson arbitrary waveform synthesizer

“…Because we compare the JAWS to itself, the frequencydependent cable error cannot be observed in this measurement. The arrangement of the three DCB and the 3 dB attenuator form a two-pole high-pass filter, reducing I FT significantly [17]. Note that in this setup, I FT flows almost completely through the low side of the output cabling and the parasitic impedances therein back to ground potential.…”

“…Prior to the calibration of the noise thermometer components, we need to ensure that the JAWS is operated with minimum feedthrough error and at its quantum locking range (QLR). The measurement of the feedthrough error and QLR of the JAWS is performed in a similar manner to [17], except that we compare the JAWS to itself instead of using a second identical JAWS. The QLR is the range of pulse-bias amplitudes where the signal amplitude remains constant, i.e.…”

“…After calibration, we can now derive a 0 and thus T from the spectra S V at different signal amplitudes and/or waveforms. Note that the calibration fit also includes the cable error and any remaining feedthrough error of the JAWS which both have a dominant quadratic frequency dependence and only negligible higher-order components [17]. However, this has an insignificant effect on the final result because the data analysis removes any contribution with a quadratic frequency dependence.…”

Calibration of the dual-mode auto-calibrating resistance thermometer with few-parts-per-million uncertainty

“…The setup used in this work is similar to that of previous measurements. It provides optimal shielding and effectively mitigates systematic amplitude deviations that occur in a JAWS at higher signal frequencies (see [14,20] for more details).…”