Hybrid high temperature superconductor/GaAs 10 GHz microwave oscillator: temperature and bias effects

Abstract

phase noise = -68 dBc/Hz at 10 kHz from the carrier for the gold version. CONCLUSIONOur 12-GHz hybrid HTS/SC oscillator operating at 77 K exhibits a phase noise of -75 dBc/Hz at 10 kHz from the carrier, which is lower than the gold/SC one. A value of -68 dBc/Hz has been reported by Rohrer, Valco, and Bhasin [3] for a microstrip HTS/SC oscillator on a single substrate. It allows us to expect even improved performance for our oscillator, which will be quasiintegrated on a single substrate, with a transistor transplanted by expitaxial lift off or flip-chip techniques [4]. The design of the circuit packaging is also under study to avoid radiation losses. ACKNOWLEDGMENTSWe would like to thank J. C. Villegier and L. Arnaud from LET1 (Grenoble, France) for the deposition of the YBaCuO film A414 (sample B). ABSTRACTA time-frequency super-resolution procedure is presented for processing wideband backscattered data containing dispemwe surface-wave effects. This approach i s based on repeatedly applying the ESPRIT method to a sliding window of fiquency data. The mw poles returned by ESPRIT produce a more sharply resolved time-frequency &play than that of the short-rime Fourier transform. One inherent limitation of ESPRIT is that it findr a multitude of poles for a single disperswe scattering mechanism. l%is limitation is overcome by properly combining the mw poles comsponding to each disperswe mechanism This pok-combining approach recovers the hue frequency behavior of each disperswe mechanism and allows a complete parameter estimation of the data to be performed. ABSTRACTThe basic topology ir a series of transverse dipoles coupled electromagnetically to a microstrip line. A#er modeling each element with a numerical technique (MOM), this array is modeled with an equivalent

An X-band HEMT microwave oscillator stabilized with a superconducting resonator

“…The sensitivity of the frequency to temperature of −2 kHz K −1 at 77 K is measured. This is two orders smaller than the rate of change of the frequency as a function of temperature of a ring resonator patterned with YBa 2 Cu 3 O 7 [1].…”

“…Such drift would be most severely felt in narrow-band circuits or applications requiring a high degree of stability. Operation of YBaCuO film resonators at 77 K is on the edge of this region and may provide adequate stability depending on the requirements of the circuit [1]. This motivates an attempt to demonstrate the potential application of HTS to a hybrid oscillator, integrating a Tl microstrip resonator on an LaAlO 3 substrate (ε r = 24.5).…”

“…Different approaches to circuit implementation have already been discussed [1][2][3][4][5][6]. A conventional parallel feedback design on an RT/Duroid substrate (ε r = 10.4) is chosen for the oscillator topology, due to the simplicity of incorporating a resonator implemented onto a 5 mm×5 mm LaAlO 3 substrate.…”

High-efficiency Ku-band oscillators

“…Touchstone was used to combine the three-port -parameter file with the gate, source, and load -parameter files. Similar to the approach by Rohrer et al, the peak of the input reflection coefficient looking into the drain of the pHEMT was found by varying the length of the open-circuit microstrip lines on the source and gate [21]. The substrate used for the oscillator circuit is Rogers RO4350 (height mm, , loss tangent , and Cu conductor thickness mm).…”

A Low Phase Noise All Cryogenic Microwave Oscillator Based on a Superconductor Resonator

“…It degrades with f 2 when the frequency increases and this explains why HTS technology performs better in the low microwave range. Contrarily to the first projects on hybrid superconductor oscillators in the 1990s [7,8], we have chosen to work at 1 GHz, which allows to reach unloaded quality factors higher than 200 000 for this type of resonator at 77 K [9,10]. Besides, 1 GHz is a popular frequency to generate frequency combs used to stabilize synthesizers in the whole microwave range.…”