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**1 - 3**of**3**### A Four-Transistor Level Converter for Dual-Voltage Low-Power Design

, 2014

"... Power dissipation in digital circuits has become a primary concern in electronic design. With increasing usage of portable devices, there are severe restrictions being placed on the size, weight and power of batteries. In this work, we propose a design of a dual V th feedback type four-transistor l ..."

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Power dissipation in digital circuits has become a primary concern in electronic design. With increasing usage of portable devices, there are severe restrictions being placed on the size, weight and power of batteries. In this work, we propose a design of a dual V th feedback type four-transistor level converter (DVF4) with reduced delay and power overheads. The use of DVF4 enhances the effectiveness of a dual-voltage low-power design. The level converter can be used in a circuit with multi supply voltage system where low supply gates may feed into high supply gates resulting in lower power and higher speed than with previously published level converters. The proposed level converter is based on a feedback circuit and employs multi-V th technique. To portray the advantages, we compare the proposed level converter with a previously published level converter for various supply voltages and observe 17.44% to 53% power savings and around 50% delay reduction over the best 32 nm CMOS design available in the literature. The impact of process variations is also examined. When used with dual VDD designs, the new level converter renders up to 61% more energy savings for benchmark circuits in comparison when level converters are not allowed. Furthermore, a level converter flip-flop combination performs better than an existing level converting flip-flop. A single-threshold alternative of the new level converter still remains effective, though over a reduced voltage range.

### Energy-Efficient Dual-Voltage Design Using Topological Constraints

, 2013

"... We propose a method for dual supply voltage digital design to reduce energy consumption without violating the given performance requirement. Although the basic idea of placing low voltage gates on non-critical paths is well known, a new two-step procedures does it so more efficiently. First, given a ..."

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We propose a method for dual supply voltage digital design to reduce energy consumption without violating the given performance requirement. Although the basic idea of placing low voltage gates on non-critical paths is well known, a new two-step procedures does it so more efficiently. First, given a circuit and its nominal single supply voltage, we find a suitable value for a lower second supply voltage that is likely to give the best advantage in power reduction. Besides, using the critical path timing constraint and a linear-time gate slack calculation we also classify gates into three groups. All gates in Group 1 can be simultaneously assigned the lower voltage. Any gate in Group 2 can be assigned the lower voltage but then gate slacks must be recalculated because the group classifications may change. No gate in Group 3 can be assigned the lower voltage. A second step then assigns the lower voltage to the largest possible number of gates using the gate classifications and imposing a topological constraint, preventing any low voltage gate from feeding into a higher voltage gate, thus avoiding the use of level converters. SPICE simulation of dual-voltage ISCAS’85 benchmark circuits using the 90nm bulk CMOS PTM (predictive technology model) shows energy savings of up to 60 % with no increase in the original critical path delay and up to 70 % with relaxed critical path delay.

### Dual-Threshold Design of Sub-threshold Circuits

"... Abstract—Dual threshold voltage (Vth) design is a common method for reducing leakage power in above-threshold circuits. This research shows that it is also effective in reducing energy per cycle of sub-threshold circuits. We first study the single-Vth design theoretically and by simulations, and fin ..."

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Abstract—Dual threshold voltage (Vth) design is a common method for reducing leakage power in above-threshold circuits. This research shows that it is also effective in reducing energy per cycle of sub-threshold circuits. We first study the single-Vth design theoretically and by simulations, and find that the energy per cycle is independent of threshold voltage. However, in a dual-Vth design, the energy per cycle depends on both threshold voltage and supply voltage. We propose a framework to further reduce energy per cycle below what is possible with a single Vth. Given a nominal value for Vth, we determine an optimal supply voltage Vdd and an optimal higher Vth. Application to a 32-bit ripple carry adder shows energy saving of 29 % over the single-Vth lowest energy. I.