Browsing by Author "Eker, Taylan"

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    Design and implementation of A 06 GHz - 09 GHz RF-SQUID Read-out system and investigation of rf-SQUID signal characteristics
    (2005) Eker, Taylan
    Design and implementation of a transceiver system for rf-SQUID (Superconducting Quantum Interference Device) operation is investigated in this work. Besides, experiments to characterize the rf-SQUID have been performed using the implemented system. The steps in system design and implementation are presented. The difficulties and drawbacks of the system are reported and alternative techniques required to overcome these problems are determined. Also, for the operation of the rf-SQUID at much higher frequencies, different transceiver architecture is proposed and possible drawbacks are stated. Using implemented system, several experiments were performed on two high Tc rfSQUID gradiometers with a tank-circuit resonating at 720 MHz. In these experiments, the frequency and amplitude of the applied rf signal were swept and output flux to voltage transfer signal (modulation added by rf-SQUID), Vspp, and incoming rf signal spectrum are reported and analyzed.
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    Effect of rf pumping frequency and rf input power on the flux to voltage transfer function of rf-SQUIDs
    (IEEE, 2007) Akram, Rizwan; Eker, Taylan; Bozbey, Ali; Fardmanesh, Mehdi; Schubert, J.; Banzet, M.
    We present the results on the correlation between the flux to voltage transfer function, Vspp, of the rf-SQUID and the rf-bias frequency as well as rf-bias power. Measurements were performed for different SQUID gradiometer samples chosen from the same batch or different batches. In order to have full control on the electronics parameters, an experimental rf-SQUID circuit was designed and implemented with an operation frequency of 600 MHz to 900 MHz. According to our findings, It has been observed that at any particular rf-bias power, Vspp vs. rf-bias frequency shows Sine-like behavior. We observed that the main lobe maxima exist close to the resonance frequency of the LC tank circuit and by changing only the power, amplitude of the main lobe and side lobes can be controlled. The Vspp vs. rf-bias power analysis shows that maximum of Vspp, strongly depends on the bias frequency. This can be correlated with the S11 parameter of LC tank circuit. We also observed that the devices from the same batch show main lobe maxima at different frequencies and/or power. Our SQUIDs with high working frequency gave their maxima at lower rf-bias powers leading to the need of having high frequency electronics with low bias power handling capabilities. It has also been observed that the SQUIDs from the same chip show similar characteristics regarding Vspp vs. frequency and power while the SQUIDs from different batches show completely different behavior for a fixed LC tank circuit configuration.