The scaling of transistor sizes has resulted in dramatic increase of leakage currents. The sub-threshold and gate leakages have now become a major contributor to total power dissipations. This paper presents two flip-flops based on dual-threshold CMOS and multiple leakage reduction techniques to reduce their leakage dissipations. In the DT-TG FF (Dual-Threshold Transmission Gate Flip-Flop), some transistors on non-critical paths use high-threshold devices to reduce their leakage currents, while the other transistors on critical paths use low-threshold devices to maintain performance. The MLRT FF (Multiple Leakage Reduction Technique Flip-Flop) uses P-type CMOS techniques, MTCMOS (Multi-Threshold CMOS) power-gating and dual-threshold technique to reduce both sub-threshold and gate leakage dissipations. Taken as an example, a practical sequential system realized with the two low-leakage flip-flops is demonstrated using a mode-5 × 5 × 5 counter. The simulation results show that the two flip-flops achieve considerable leakage reductions.
Independent-Gate (IG) FinFET is a promising device in circuit applications due to its two separated gates, which can be used independently. In this paper, we proposed a comprehensive method to optimize the Dual Threshold (DT) IG FinFET devices by carrying out modulations for the gate electrode work function, oxide thickness, and silicon body thickness. Titanium nitride (TiNx) is used as the tunable work function gate electrode for good performances. The thicknesses of the gate oxide and silicon body are swept by TCAD simulations to obtain the appropriate values. The verification simulation of the optimized transistors shows that the DT IG FinFETs can realize merging parallel and series transistors, respectively, and the current characteristics of the transistors are improved significantly. By extracting the BSIM-IMG model parameters, we can simulate the circuits composed of the proposed DT IG FinFET by using HSPICE with BSIM-IMG model. As practical examples, we optimized two novel 7T SRAM cells using DT IG FinFETs. HSPICE simulation results indicate that the new SRAM cells obtain higher write margin and read static noise margin with lower leakage power consumption than the other implementations.
Abstract-MOS Current-Mode Logic (MCML) is usually used for high-speed applications. However, the large static power dissipation of MCML circuit limits its application in portable devices. In this work, we proposed a power-gating (PG) technique to reduce the standby power of the near-threshold MCML. The PG 1-bit full adder and a mod-10 counter are designed and simulated using HSPICE at 45nm CMOS technology with predictive technology model (PTM) model. The simulation results show that the standby power of the PGadder and PG-counter is only 1.0nW and 3.0 nW, respectively. And the performance of the PG MCML circuits does not deteriorate.
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