[Show abstract][Hide abstract] ABSTRACT: We developed and fabricated series arrays of overdamped SNS Josephson junctions for AC Josephson voltage standards (S: superconductor, N: normal conductor). The junctions are based on Nb(x)Si(1-x) barriers allowing nearly independent tuning of critical current density and characteristic voltage by varying niobium content and thickness of the barrier. We optimised the junction barrier deposition for the co-sputtered Nb x Si 1-x so that we are able to fabricate Josephson junction series arrays with up to 69,632 junctions for output voltages up to 10 V under 70 GHz microwave irradiation. The width of the constant-voltage steps at 10 V exceeds 1 mA for a typical critical current of about 3 mA.
[Show abstract][Hide abstract] ABSTRACT: Different types of intrinsically shunted Josephson junctions have been developed and investigated for ac voltage standard applications at PTB. The first type, for generation of voltages up to 10 V, is driven by a 70 GHz sinusoidal microwave signal and consists of 69,632 series-connected junctions, where the number of junctions per segment follows a binary sequence. The second type, which is driven by short current pulses, contains up to 5,000 junctions and enables the synthesis of intrinsically accurate ac wave-forms.
[Show abstract][Hide abstract] ABSTRACT: Superconductor-normal metal-superconductor(SNS) Josephson junction series arrays are developed and investigated for applications in the Josephson arbitrary waveform synthesizer (JAWS). The series arrays contain up to about 10 000 junctions arranged in a meanderlike design. AC voltages and arbitrary waveforms are synthesized by operation of the Josephson junctions by short current pulses. Higher harmonics are at least 110 dB below the fundamental. To verify the generated waveforms, a spectrum analyzer that has initially been calibrated using a binary-divided programmable Josephson voltage standard is used.
IEEE Transactions on Instrumentation and Measurement 05/2009; 58(4-58):797 - 802. DOI:10.1109/TIM.2008.2007033 · 1.79 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: AC voltages and arbitrary waveforms are synthesized by Josephson junctions operated by short current pulses. Series arrays of intrinsically shunted SNS Josephson junctions were developed and investigated for applications in this Josephson Arbitrary Waveform Synthesizer (JAWS). Amplitudes above 200 mV were generated by series arrays consisting of more than 10,000 junctions arranged in a meander-like design.