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Design and Optimization of T1 Flip Flop in Bi-Directional RSFQ Logic

Jabbari, Tahereh | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 47314 (55)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Fardmanesh, Mehdi
  7. Abstract:
  8. Superconducting Rapid Single Flux Quantum (RSFQ) Logic, is very fast (up to about THz) and ultra low power circuit technology and is the most recent and fastest superconducting logic family. So far one of the difficulties in RSFQ logic is associated to reading the circuit states in particular flip flops. In prevalent RSFQ logic using T1 Flip Flop gate instead of the T Flip Flop, the non-destructive reading of the registered bit is possible. Through this approach, it also has some limits in particular circuits. Another idea of resolving this issue, is considering the very new bi-directional RSFQ logic, which is based on alternative changing the bias current through the Josephson junctions. Due to the shifting bias current in bi-directional RSFQ circuits, the classic T1 gate does not work properly and after reading the memory, resets its value to zero. We have investigated the readout cell based on TFF, in this new scheme. By simulation of the circuit, we have studied the effects of the modifying parameters and current levels of the junctions. As a result, we found that the critical current and area size of the junctions have an important role in the response profile of the cell and correct functioning of the cell. We have also investigated the effect of the width of an input pulse on the response of the cell. We have also studied the loading effect on the behavior of the circuit. We have also examined the fluctuations in the pulses with respect to changing the parameters. For correct reading from the memory with minimum delay and fluctuations, we have designed a suitable NDRO cell. We have examined the cell behavior in positive and negative half cycles while the cell is stable and has a proper operation. Hence in this work this gate is redesigned and optimized for bi-directional RSFQ NDRO circuits, which can store the information bit in its memory while at any time it can read its content by the readout part without destroying the state of the memory
  9. Keywords:
  10. Bidirectional ; Flip Flop ; Superconductive Logic ; Rapid Single Flux Quantum (RSFQ) ; Flip Flop T1 ; Non-Destructive Read-Out Part

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