In this paper, a two dimensional analytical model of the threshold voltage for HGD TFET structure has been proposed. We have also presented the analytical models for the tunneling width and the channel potential. The potential model is used to develop the physics based model of threshold voltage by exploring the transition between linear to exponential dependence of drain current on the gate bias. The proposed model depends on the drain voltage, gate dielectric near the source and drain, silicon film thickness, work function of gate metal and oxide thickness. The accuracy of the proposed model is verified by simulation results of 2-D ATLAS simulator. Due to the reduction of the equivalent oxide thickness, the coupling between the gate and the channel junction enhances which results in lower threshold voltage. Tunneling width becomes narrower at a given gate voltage for the optimum channel concentration of 1016 /cm3. The higher concentration in the source (Ns) causes a steep bending in the conduction and valence bands compared to the lower concentration which results in smaller tunneling width at the source-channel interface.

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This paper presents an implementation of comparator (1-bit) circuit using a MUX-6T based adder cell. MUX-6T full adder cell is designed with a combination of multiplexing control input and Boolean identities. The proposed comparator design features higher computing speed and lower energy consumption due to the efficient MUX-6T adder cell. The design adopts multiplexing technique with control input to alleviate the threshold voltage loss problem which is commonly encountered in Pass Transistor Logic (PTL) design. The proposed design successfully embeds the buffering circuit in the full adder design which helps the cell to operate at lower supply voltage compared with the other related existing designs. It also enhances the speed of the cascaded operation significantly while maintaining the performance edge in energy consumption. In the proposed design, the transistor count is minimized. For performance comparison, the proposed MUX-6T comparator (1-bit) is compared with four existing full adders based comparators using BSIM4 model parameters. The simulations are performed for 65nm process models indicate that the proposed design has lowest energy consumption along with the performance edge in both speed and energy consumption. The variants namely area and power of the proposed comparator is also compared with the published author designs to validate its suitability for low power and high speed mobile communication applications.

Comparator is a basic arithmetic component in a digital system and adders are the basic block of processor unit, the performance of adder will improve the system performance. The proposed 11T adder comparator is consists of three main components, namely XOR, inverter, and MUX logic. The circuit is designed and implemented based on top-down approach with 11 transistors. The proposed cell can be used at higher temperature with minimal power loss. It also gives faster response for the carry output. The proposed comparator circuit shows 63.80% improvement in power consumption than other circuits.