Browsing by Author "Ekinci, Ahmet Suat"
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Item Open Access Circuit theoretical methods for efficient solution of finite element structural mechanics problems(Bilkent University, 1999) Ekinci, Ahmet SuatShrinking device dimensions in integrated circuit technology made integrated circuits with millions of components a reality. As a result of this advance, electrical circuit simulators that can handle very large number of components have emerged. These programs use new circuit simulation techniques which approximate the system with reduced order models, and can find solutions accurately and quickly. This study proposes formulating the structural mechanics problems using FEM, and then employing the recent speedup techniques used in circuit simulation. This is obtained by generating an equivalent resistor-inductor-capacitor circuit containing controlled sources. We analyze the circuits with general-purpose circuit simulation programs, HSPICE, and an in-house developed circuit simulation program, MAWE, which makes use of generalized asymptotic waveform evaluation (AWE) technique. AWE is a moment matching technique that has been successfully used in circuit simulation for solutions of large sets of equations. Several examples on the analysis of the displacement distributions in rigid bodies have shown that using circuit simulators instead of conventional FEM solution methods improves simulation speed without a significant loss of accuracy. Pole analysis via congruence transformations (PACT) technique is a recent algorithm used for obtaining lower order models for large circuits. For a further reduction in time, we employed a similar algorithm in structural mechanics problems before obtaining the equivalent circuit. The results are very promising.Item Open Access Digital dual tone multifrequency receiver(Bilkent University, 1994) Ekinci, Ahmet SuatIn this thesis, a suitable algorithm for detection of Dual Tone Multifrequency tones is proposed and implemented as a VLSI chip. The algorithm is based on an approximation of correlation. The input signal is correlated with the hardlimited versions of three sinusoids having 7Ty^3 phase difference. Also, a level detector is added to the algorithm. The algorithm only requires addition and subtraction, but no multiplication; and this reduces the complexity of the circuit. The implementation of the algorithm proposed has been realized as a fully integrated digital DTMF receiver chip using semi-custom layout techniques. The final chip is fabricated in 1-^m CMOS technology, and it has a total area of 24.78 mm^.