VHF Josephson Arbitrary Waveform Synthesizer, IEEE Transactions on Applied Superconductivity

Description

These data will appear in [1]. The abstract for that paper is given below:We report on the design, fabrication, and measurement of a Very High Frequency band Josephson Arbitrary Waveform Synthesizer (VHF-JAWS) at frequencies from 1~kHz to 50.05~MHz. The VHF-JAWS chip is composed of a series array of 12,810 Josephson junctions (JJs) embedded in a superconducting coplanar waveguide. Each JJ responds to a pattern of current pulses by creating a corresponding pattern of voltage pulses, each with a time-integrated area related to fundamental constants as $ extit{ extbf{h/2e}}$. The pulse patterns are chosen to produce quantum-based single-tone voltage waveforms with an open-circuit voltage of 50~mV~rms (\mbox{-19.03~dBm} output power into 50~$\Omega$ load impedances) at frequencies up to 50.05~MHz, which is more than twice the voltage that has been generated by previous RF-JAWS designs at 1~GHz. The VHF-JAWS is "quantum-locked", that is, it generates one quantized output voltage pulse per input current pulse per JJ while varying the dc current through the JJ array by at least 0.4~mA and the amplitude of the bias pulses by at least 10~\%. We use the large bias pulse quantum-locking range to investigate one source of error in detail: the direct feedthrough of the current bias pulses into the DUT at VHF frequencies. We reduce this error by high-pass filtering the current bias pulses and measure the error as a function of input pulse amplitude using two techniques: by measuring small changes over the quantum-locking range and by passively attenuating the input pulse amplitude so that the nonlinear JJs no longer generate voltage pulses while the error is only linearly scaled.

Resources

Name Format Description Link
8 DC bias current QLRs. RMS voltage magnitude (mV) vs DC offset (mA) 50 kHz, 150 kHz, 5.5 MHz, 15.05 MHz, 30.05 MHz, and 50.05 MHz waveforms. Voltage measurements for the 30.05 MHz tone are offset by +5.5 mV for visual clarity. https://data.nist.gov/od/ds/mds2-3156/fig5_top_dc_qlr.csv
8 The x-intercepts of the fits in fig8_top are plotted in AWG V_(p-p). We observe a non-zero x-intercept above ~6 MHz. Fit x-intercept errors included in AWG V_(p-p). https://data.nist.gov/od/ds/mds2-3156/fig8_bottom_x_intercept.csv
47 Readme for the navigation, organization, and content for the data in the figures included in the VHF Josephson Arbitrary Waveform Synthesizer manuscript. https://data.nist.gov/od/ds/mds2-3156/Readme.txt
8 The magnitude of the complex slope of the measured feedthrough error as a function of pulse amplitude (over 0.4-0.5 AWG V_(p-p)) as a function of output waveform frequency (MHz). The complex slope calculated from the change in the measured output voltage while the system is quantum-locked (qlr_slopes_mag, (mV / AWG V_(p-p))) agrees with that of the 10 dB-adjusted feedthrough error measured directly by significantly attenuating the pulses (feed_slopes_mag, (mV / AWG V_(p-p))) to remove the JJ voltage contribution. Standard uncertainties of the slope magnitudes based on the linear regression are included in mV / AWG V_(p-p). https://data.nist.gov/od/ds/mds2-3156/fig7_top_slope_mag.csv
8 Measured voltage spectra of a typical 50.05 MHz JAWS output waveform. The first row contains column headers. The first column contains the spectrum frequency data in Hertz. The second column contains the power at each frequency in dBm. The output power of the fundamental tone at 50.05 MHz is measured to be -19.3 dBm. https://data.nist.gov/od/ds/mds2-3156/fig4_50.05_MHz_spectrum.csv
8 The phase of the complex slope of the measured feedthrough error, relative to the output waveform phase at 0.43 AWG, as a function of pulse amplitude (over 0.4-0.5 AWG) as a function of output waveform frequency (MHz). The complex slope calculated from the change in the measured output voltage while the system is quantum-locked (qlr_slopes_phase, Radians normalized to JJ voltage) agrees with that of the 10 dB-adjusted feedthrough error measured directly by significantly attenuating the pulses (feed_slopes_phase, Radians normalized to JJ voltage) to remove the JJ voltage contribution. Fit errors included in Radians. https://data.nist.gov/od/ds/mds2-3156/fig7_bottom_slope_phase.csv
8 The magnitude of the complex slope of the measured feedthrough error as a function of pulse amplitude (over 0.4-0.5 AWG) as a function of output waveform frequency (MHz). The complex slope calculated from the change in the measured output voltage while the system is quantum-locked (qlr_slopes_mag, (mV / AWG V_(p-p))) agrees with that of the 10 dB-adjusted feedthrough error measured directly by significantly attenuating the pulses (feed_slopes_mag, (mV / AWG V_(p-p))) to remove the JJ voltage contribution. Fit errors included in mV / AWG V_(p-p). https://data.nist.gov/od/ds/mds2-3156/fig7_top_slope_mag.csv
8 RMS voltage magnitude (mV) measured by the DUT digitizer at the pattern frequency which is entirely due to the feedthough error (at several frequencies up to 50 MHz). This voltage is plotted versus programmed peak-to-peak pulse amplitude (AWG V_(p-p)). Data is taken after inserting 10 dB of additional attenuation so that the JJs do not contribute to the voltage waveform. The data has been scaled by 10 dB to show the error during normal operation. We perform linear regressions of the rms voltage (fit_direct_feed_mV, fit_direct_feed_pulse_amp) over the previously identified global pulse amplitude QLR (0.4-0.5 AWG). https://data.nist.gov/od/ds/mds2-3156/fig8_top_direct_feed.csv
8 Frequency dependence of the measured digitizer voltage generated by the VHF-JAWS from 1 kHz to 50.05 MHz (transfer_function_freq (Hz)). The rms voltage (transfer_function_voltage (mV)) measured across the 50 Ohm input impedance of the digitizer is used to calculate the output power (transfer_function_power (dBm)). This data was taken at an RF AWG bias pulse amplitude of 0.43 and a dc bias current of zero. https://data.nist.gov/od/ds/mds2-3156/fig3_transfer_function.csv
8 DC bias current QLRs. The first three columns are the flattened data for a density plot of the total harmonic distortion (dBc) versus DC offset current (mA) for waveform frequencies up to 50.05 MHz. The last three columns are data for the black dashed scatter plot, which denotes the QLR margin minimum (mA) and QLR margin maximum (mA). All data is taken at a default RF AWG pulse amplitude (0.43 AWG V_(p-p)). https://data.nist.gov/od/ds/mds2-3156/fig5_bottom_dc_qlr.csv
8 DC bias current QLRs. RMS voltage magnitude (mV) vs DC offset (mA) 50 kHz, 150 kHz, 5.5 MHz, 15.05 MHz, 30.05 MHz, and 50.05 MHz waveforms. The rms voltage values for the 30.05 MHz tone shown here and in the figure are +5.5 mV higher than the measured values. This addition was included for visual clarity. https://data.nist.gov/od/ds/mds2-3156/fig5_top_dc_qlr.csv
8 Pulse amplitude QLRs. RMS voltage magnitude (mV) vs programmed peak-to-peak amplitude (AWG V_(p-p)) for 50 kHz, 150 kHz, 5.5 MHz, 15.05 MHz, 30.05 MHz, and 50.05 MHz waveforms. The rms voltage values for the 30.05 MHz tone shown here and in the figure are +5.5 mV higher than the measured values. This addition was included for visual clarity. https://data.nist.gov/od/ds/mds2-3156/fig6_top_pulse_amp_qlr.csv
8 Pulse amplitude QLRs. Total harmonic distortion (dBc) vs programmed peak-to-peak amplitude (AWG V_(p-p)) for 50 kHz, 150 kHz, 5.5 MHz, 15.05 MHz, 30.05 MHz, and 50.05 MHz waveforms. https://data.nist.gov/od/ds/mds2-3156/fig6_bottom_pulse_amp_qlr.csv
8 The phase of the complex slope of the measured feedthrough error, relative to the output waveform phase at 0.43 AWG, as a function of pulse amplitude (over 0.4-0.5 AWG V_(p-p)) as a function of output waveform frequency (MHz). The complex slope calculated from the change in the measured output voltage while the system is quantum-locked (qlr_slopes_phase, Radians normalized to JJ voltage) agrees with that of the 10 dB-adjusted feedthrough error measured directly by significantly attenuating the pulses (feed_slopes_phase, Radians normalized to JJ voltage) to remove the JJ voltage contribution. Standard uncertainties of the slope phases based on the linear regression are included in Radians. https://data.nist.gov/od/ds/mds2-3156/fig7_bottom_slope_phase.csv
8 The x-intercepts of the fits in fig8_top are plotted in AWG V_(p-p). We observe a non-zero x-intercept above ~6 MHz. Standard uncertainties of the x-intercepts based on the linear regression are included in AWG V_(p-p). https://data.nist.gov/od/ds/mds2-3156/fig8_bottom_x_intercept.csv
8 RMS voltage magnitude (mV) measured by the DUT digitizer at the pattern frequency which is entirely due to the feedthough error (at several frequencies up to 50 MHz). This voltage is plotted versus programmed peak-to-peak pulse amplitude (AWG V_(p-p)). Data is taken after inserting 10 dB of additional attenuation so that the JJs do not contribute to the voltage waveform. The voltages shown here, and in the figure, are scaled up by +10 dB from the measured voltages (they are 10 dB larger) to show the feedthrough error during normal operation. We perform linear regressions of these voltages (fit_direct_feed_mV, fit_direct_feed_pulse_amp) over the previously identified global pulse amplitude quantum locking range (0.4-0.5 AWG V_(p-p)). https://data.nist.gov/od/ds/mds2-3156/fig8_top_direct_feed.csv
8 Measured voltage spectra of a typical 50.05 MHz JAWS output waveform. The first row contains column headers. The first column contains the spectrum frequency data in megahertz. The second column contains the power at each frequency in dBm. The output power of the fundamental tone at 50.05 MHz is measured to be -19.3 dBm. https://data.nist.gov/od/ds/mds2-3156/fig4_50.05_MHz_spectrum.csv

Tags

  • superconducting-microwave-devices
  • power-measurement-standards
  • superconducting-integrated-circuits
  • signal-synthesis
  • josephson-junction-arrays
  • digital-analog-conversion

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