Browsing by Author "Dr.Paul Franzon, Committee Chair"

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    Application of Body Biasing and Supply Voltage Scaling Techniques for Leakage Reduction and Performance Improvements of CMOS Circuits
    (2008-12-20) Devasthali, Vinayak Sudhakar; Dr.Paul Franzon, Committee Chair; Dr. Kevin Gard, Committee Member; Dr. W. Rhett Davis, Committee Member
    The efficiency of body biasing technique is evaluated in 90-nm process technology for regular and low threshold voltage devices. A new leakage monitor circuit for detecting an optimum reverse body bias voltage is designed. The simulation results shows that the monitor circuit accurately tracks the leakage currents within +/-5% of the actual leakage current values. The standby leakage reduction in static CMOS circuits using reverse body biasing is presented. The results indicate that the reverse body biasing is more beneficial for high speed circuits using low threshold voltage devices. For circuits using nominal threshold voltage devices, the efficiency of reverse body biasing decreases due to the presence of gate leakage. Speed improvement in ring oscillator and ripple carry adder using forward body bias is measured. The results show that the forward body biasing is less effective due to the lower body effect parameter. Supply voltage scaling technique for active power reduction is implemented using 180-nm technology. Power savings up to 50% is achieved by scaling the supply voltage as per the operating frequency requirements.
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    Inductively Coupled Connectors
    (2009-03-04) Chandrasekar, Karthik; Dr.Paul Franzon, Committee Chair; Dr. Michael Steer, Committee Member; Dr. Gianlucca Lazzi, Committee Member; Dr. J.P Maria, Committee Member
    CHANDRASEKAR, KARTHIK. INDUCTIVELY COUPLED CONNECTORS (under the direction of Dr. Paul Franzon) AC coupled interconnects show promise to enable multi-gigabit/second data rates between high pin count IC’s within a multi-chip module, while achieving significant power savings as well [3]. AC Coupling can be realized with planar inductive or capacitive elements. Inductive coupling offers many degrees of freedom for system design by varying geometric parameters to tune parasitic elements in the model, such as: the crossover capacitance between the spirals, the magnetic coupling coefficient, winding resistance, inductance ratio and impedance terminations. So far, inductively coupled interconnects have mainly shown potential for multi-Gbps signaling only in level 1 interconnections, i.e. direct chip to chip communication and 3D IC’s. Multi-Gbps pulse signaling is demonstrated with inductively coupled interconnects across packaging interfaces in this dissertation. This shows feasibility of realizing sub-mm pitch, true Zero Insertion Force (ZIF) surface mount connectors and sockets (i.e. level 2 and level 3 interconnections). Inductors are fabricated on two opposing surfaces, e.g. the faces of a connector or socket. When mated, they form a transformer, which is used to carry signals through the mated interface. The main advantage of building a separable connection this way, is that it is possible to achieve a high density with a simple mechanical structure. This in turn, offers potential for cost reduction and support for true three dimensional packaging. Being a true zero-insertion force interface, very high pin counts could be easily supported. ZIF sub-mm pitch surface mount inductive connector technology also addresses some of the signal integrity problems inherent in pressfit style connectors. It is difficult to use capacitive coupling for this application, because the structure is placed in the transmission line, not at one end. Thus both the driving impedance and load being driven is 50 ohms. The high, frequency-dependent impedance of a series capacitor would lead to reflection noise (i.e. return loss). Unless large capacitors or lossy codes guaranteeing only high frequency content are used, the transmitted swing would be too small (i.e. excessive insertion loss). In contrast, inductively coupled connectors can achieve broad band matching impedance and give acceptable values to return and insertion losses. Methods to optimize signal integrity are discussed in detail for inductively coupled systems in this dissertation. The signaling data rate achieved in this system is from 1 Gbps to 8.5 Gbps, which depends on the 3 dB coupling frequency of the composite channel consisting of the inductive interconnections and the transmission lines.