Accession Number : AD0769222

Title :   Conversion Gain and Noise in a Josephson Mixer.

Descriptive Note : Technical rept.,

Corporate Author : CALIFORNIA UNIV BERKELEY DEPT OF PHYSICS

Personal Author(s) : Taur,Yuan ; Claassen,John H. ; Richards, Paul L.

Report Date : OCT 1973

Pagination or Media Count : 28

Abstract : Fundamental mixing at 36 GHz in non-hysteretic Nb point contacts has been observed with overall conversion efficiencies in the range 0.33 < or = eta < or = 4 and mixer noise temperatures in the neighborhood of ( Taub M) approximately 200K. The observed conversion efficiencies are in good agreement with the Resistively Shunted model. The observed noise can be accounted for by assuming that the Johnson noise in the shunt resistor is the only source of noise driving the junction. Somewhat larger noise is seen from resonantly coupled mixers than is seen when the mixer is driven from an rf current source. Fundamental mixing in hysteretic junctions is limited to a narrow if bandwidth and gives much larger conversion gain but also larger noise. Parametric amplification at the if frequency is seen in hysteretic junctions. Fourth order harmonic mixing with omega sub (LO)/2 pi at 9GHz has been achieved with performance almost comparable to fundamental mixing. Cavity mode mixing appears less promising. (Author)

Descriptors :   (*Mixers(Electronics), *Josephson junctions), Heterodyning, Superconductors, Detectors, Microwaves, Infrared detectors, Gain, Noise(Electrical and electromagnetic)

Subject Categories : Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE