Browsing by Author "Erdem, Aykut"

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Open Access
MMIC VCO design
(1995) Erdem, Aykut
In this study, three voltage controlled oscillator (VCO) circuits are realised using Monolithic Microwave Integrated Circuit (MMIC) technology. Two of the VCOs are in the capacitive feedback topology, whereas the last one is designed by using the inductive feedback topology. GaAs MESFETs are used as both active devices and varactor diodes. Designed for a 50il system, the circuits operate in 8.88-10.40GHz, 8.7T10.23GHz and 8.96-12.14GHz ranges. Their output powers are well above the 9.5dBm for most of the oscillation band. All three VCOs have harmonic suppressions better than 30dBc. Both small signal and large signal analysis are carried out. The layouts are designed by GEC Marconi’s F20 process rules and the circuits are produced in this foundry
Open Access
Multi-contrast MRI synthesis with channel-exchanging-network
(IEEE, 2022-08-29) Dalmaz, Onat; Aytekin, İdil; Dar, Salman Ul Hassan; Erdem, Aykut; Erdem, Erkut; Çukur, Tolga
Magnetic resonance imaging (MRI) is used in many diagnostic applications as it has a high soft-tissue contrast and is a non-invasive medical imaging method. MR signal levels differs according to the parameters T1, T2 and PD that change with respect to the chemical structure of the tissues. However, long scan times might limit acquiring images from multiple contrasts or if the multi-contrasts images are acquired, the contrasts are noisy. To overcome this limitation of MRI, multi-contrast synthesis can be utilized. In this paper, we propose a deep learning method based on Channel-Exchanging-Network (CEN) for multi-contrast image synthesis. Demonstrations are provided on IXI dataset. The proposed model based on CEN is compared against alternative methods based on CNNs and GANs. Our results show that the proposed model achieves superior performance to the competing methods.