Records |
Author |
Loudkov, D.; Tong, C.-Y. E.; Blundell, R.; Kaurova, N.; Grishina, E.; Voronov, B.; Gol’tsman, G. |
Title |
An investigation of the performance of the superconducting HEB mixer as a function of its RF embedding impedance |
Type |
Journal Article |
Year |
2005 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
15 |
Issue |
2 |
Pages |
472-475 |
Keywords |
waveguide NbN HEB mixers |
Abstract |
We have conducted an investigation of the optimal embedding impedance for a waveguide superconducting hot-electron bolometric (HEB) mixer. Three mixer chip designs for 800 GHz, offering nominal embedding resistances of 70 /spl Omega/, 35 /spl Omega/, and 15 /spl Omega/, have been developed. We used both High Frequency Structure Simulator (HFSS) software and scale model impedance measurements in the design process. We subsequently fabricated HEB mixers to these designs using 3-4 nm thick NbN thin film. Receiver noise temperature measurements and Fourier Transform Spectrometer (FTS) scans were performed to determine the optimal combination of embedding impedance and normal-state resistance for a 50 Ohm IF load impedance. A receiver noise temperature of 440 K was measured at a local oscillator frequency 850 GHz for a mixer with normal state resistance of 62 /spl Omega/ incorporated into a circuit offering a nominal embedding impedance of 70 /spl Omega/. We conclude from our data that, for low noise operation, the normal state resistance of the HEB mixer element should be close to the embedding impedance of the mixer mount. |
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Call Number |
1439677 |
Serial |
1464 |
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Author |
Meledin, D.; Tong, C.-Y. E.; Blundell, R.; Goltsman, G. |
Title |
Measurement of intermediate frequency bandwidth of hot electron bolometer mixers at terahertz frequency range |
Type |
Journal Article |
Year |
2003 |
Publication |
IEEE Microw. Wireless Compon. Lett. |
Abbreviated Journal |
IEEE Microw. Wireless Compon. Lett. |
Volume |
13 |
Issue |
11 |
Pages |
493-495 |
Keywords |
waveguide NbN HEB mixers |
Abstract |
We have developed a new experimental setup for measuring the IF bandwidth of superconducting hot electron bolometer mixers. In our measurement system we use a chopped hot filament as a broadband signal source, and can perform a high-speed IF scan with no loss of accuracy when compared to coherent methods. Using this technique we have measured the 3 dB IF bandwidth of hot electron bolometer mixers, designed for THz frequency operation, and made from 3-4 nm thick NbN film deposited on an MgO buffer layer over crystalline quartz. |
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1531-1309 |
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Call Number |
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1509 |
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