4-Input NAND and NOR Gates Based on Two Ambipolar Schottky Barrier FinFETs

We report on four-input NAND and NOR gates using only two 7nm Schottky-Barrier (SB) independent-gate FinFETs transistors that take advantage of gate workfunction engineering (WFE). Careful optimization of workfunctions at the source/drain contacts as well as two independent gates of the SB-FinFETs provide unprecedented control of the threshold in the ambipolar device operation. It is used in this work to tailor 4-input NAND and NOR functionalities out of only two transistors (2T), utilizing only two different metal workfunctions in a given gate. Correct operation of multi-input gates for supply voltages as low as VDD = 0.5V has been verified using 2D TCAD circuit simulations. Switching performance of the proposed 4-input gates indicate that they have 45% reduction in power-delay product (PDP) as compared to the conventional 16T FinFET counterparts, which is due to substantially lower power dissipation at the expense of slower transitions. A JK Flip-Flop circuit is designed using the proposed four-input NAND gate that illustrates its advantages for the logic operation.