Fig. 1. Structure of the SQUID-based RF amplifier. One end of the input coil is left open, and the RF signal is applied to the other end of the input coil and the ground. Input RF signal Vi applied to the input coil generates current in the input coil which is converted to magnetic flux via mutual inductance Mi. To adjust the flux bias in the SQUID, DC current IΦ is applied to the SQUID.
Fig. 2. Cross-sectional view of the microstrip line. (a) Multiturn input coil is separated by a dielectric layer from the SQUID washer. (a) Side view showing the vertical structure.
Fig. 3. Structure of SQUID loop and input coil. (a) Octagonal SQUID washer and multi-turn octagonal coil. (b) Linewidth (w) and space (s) of the input coil line.
Fig. 4. Design of SQUID amplifier. (a) Whole SQUID layout. (b) Details of the design around the Josephson junction area.
Fig. 5. Package for SQUID mounting.
Fig. 6. Schematic diagram of the measurement setup.
Fig. 7. Gain curve of a SQUID amplifier.
Fig. 8. Resonance frequency vs. number of input coil turn in type-A resonator. (a) Calculated for input coil with 4 μm linewidth and 3 μm space (○), (b) measured frequency (□), and (c) recalculated frequency using the measured linewidth and space dimensions (Δ).
Fig. 9. Resonance frequency vs. number of input coil turns in type-B resonator. (a) Calculated for input coil with 8 μm linewidth and 3 μm space (○), (b) measured frequency (□), and (c) recalculated frequency using the measured linewidth and space dimensions (Δ).
Fig. 10. Resonance frequency vs. number of input coil turns in type-C resonator. (a) Calculated for input coil with 2 μm linewidth and 2 μm space (○), (b) measured frequency (□), and (c) recalculated frequency using the measured linewidth and space dimensions (Δ).
TABLE 1 MEASURED AND CALCULATED RESONANCE FREQUENCY FOR SIX MICROSTRIP SQUID AMPLIFIERS WITH DIFFERENT SQUID INDUCTANCE L AND INPUT COIL TURNS N. MODIFIED FROM [4].
TABLE 2 SQUID PARAMETERS FOR TYPE-A RESONATOR.
TABLE 3 SQUID PARAMETERS FOR TYPE-B RESONATOR.
TABLE 4 SQUID PARAMETERS FOR TYPE-C RESONATOR
참고문헌
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