A 3 mm waveband Gunn oscillator phase-locked with a high- Josephson harmonic mixer and its applications to the quantum voltage standard

Abstract

Using a high- superconducting harmonic mixer at 77 K and a phase-locking loop, a signal source (a Gunn oscillator in the 3 mm waveband) was directly phase-locked to a local oscillator for frequencies less than 1 GHz and harmonic numbers up to 120. The phase-locked Gunn oscillator achieved a frequency instability of less than Hz, with the counting time of 1 s, while the phase noise at intermediate frequency 40 MHz was ( kHz) for 120th harmonic mixing and ( kHz) for 42nd harmonic mixing. The output of this phase-locked signal source was applied to a Josephson junction array used in a voltage-standard system against which a solid-state voltage source (a Zener voltage reference) was measured. The experimental results showed that the quality of this phase-locked microwave source was good enough to justify its use in the quantum voltage standard.