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Josephson Arbitrary Waveform Synthesizer with Two Layers of Wilkinson Dividers and an FIR Filter

Published

Author(s)

Nathan E. Flowers-Jacobs, Steven B. Waltman, Anna E. Fox, Paul D. Dresselhaus, Samuel P. Benz

Abstract

The output voltage of Josephson arbitrary waveform synthesizers (JAWS) has been limited by the number of Josephson junctions (JJs) that can be driven by a single pulse generator channel. Here we double the number of JJs driven by one channel to 51 200 JJs by spreading the pulse bias between four JJ arrays using two layers of Wilkinson dividers. We use this single bias to generate a voltage at 1 kHz with an rms magnitude of 1 V. This quantum-accurate voltage was obtained over an operating current range of 1.4 mA, which is about 50% of the current range demonstrated with earlier designs that used a single layer of Wilkinson dividers and so required two pulse bias channels to generate 1 V. We also show that we can regain the original performance by adding a finite impulse response (FIR) filter, also known as an equalizer, to the pulse generator. The equalizer creates a custom transfer function that compensates for the non-ideal transfer function of the Wilkinson dividers. Optimizing the equalizer parameters increases the operating current range from 1.4 mA to 2.7 mA. This ability to drive additional JJ arrays with a single pulse generator channel will enable future JAWS chips and systems with significantly larger output voltages, which in turn will increase the voltage range for JAWS calibrations of ac thermal converters and improve precision voltage measurements that require quantum accurate, stable, distortion-free waveforms with a large signal-to-noise ratio.
Citation
IEEE Transactions on Applied Superconductivity
Volume
26
Issue
6

Keywords

Digital-analog conversion, Josephson junction arrays, Measurement standards, Signal synthesis, Superconducting integrated circuits, Voltage measurement

Citation

Flowers-Jacobs, N. , Waltman, S. , Fox, A. , Dresselhaus, P. and Benz, S. (2016), Josephson Arbitrary Waveform Synthesizer with Two Layers of Wilkinson Dividers and an FIR Filter, IEEE Transactions on Applied Superconductivity, [online], https://doi.org/10.1109/TASC.2016.2582800 (Accessed April 20, 2024)
Created June 16, 2016, Updated November 10, 2018