High Speed Full Adder Based on Modified Linear Threshold Gate and Its Application to a 4–2 Compressor

Abstract

This paper presents a modification for linear threshold gate (LTG) which belongs to the singleelectron-devices (SEDs) family. LTG enables the implementation of any linearly separable Boolean function, however, the modified LTG structure can be utilized as a multi-threshold structure. Based on proposed modified LTG structure, a novel three-input XOR gate design is presented. Then this gate is utilized in designing novel high speed full adder circuit. Since the proposed full adder has internal buffers, it is able to restore the received signals and therefore can be employed in cascaded circuit designs without fan-out concerns. The switching delay and energy consumption of the proposed full adder are analyzed and compared with previously introduced designs. The comparisons show that the proposed full adder has the shortest delay in comparison with other proposed SED full adders. Finally, a 4-2 compressor based on the proposed high speed full adder is introduced as an applicable example.

Progress on Memristor-Based Analog Logic Operation

“…Lageweg et al [43] introduced the Linear Threshold Gate (LTG), which uses tunnel junctions, capacitors, and voltage sources. It can perform any linear separable Boolean operations as [44]:…”

“…If the input weighted sum is equal to or greater than the threshold value, the output of LTG will be logical "1". Conversely, if the input weighted sum is smaller than the threshold value, the output of LTG will be logical "0" [43,44]. Voting logic, which utilizes binary inputs and equal weights, is a subset of threshold logic.…”

“…Furthermore, there are other issues to consider, e.g., hybrid memristor-CMOS-based multi-bit comparators that suffer from voltage decay [42]. Additionally, memristor-based threshold logic gates require long delay times [44] and lack effective tools for practical applications in very large-scale integration.…”

Area efficient digital logic NOT gate using single electron box (SEB)

“…Although SED utilized in many digital logic gates [10][11][12][13][14][15][16], the gate characteristics are usually limited to single gate operation and not operation in complicated designs. Some of the most used SEDs are the single electron box (SEB) and the single electron transistor (SET).…”