Current-mode Multi-valued Logic Research Articles

Low-Power Area-Efficient Fault Tolerant Adder in Current Mode Multi Valued Logic Using Berger Codes

In this paper, we propose a low-power yet area-efficient fault tolerant adder by using Berger codes. The proposed Berger code checker is designed by using the current mode multi-valued logic (CM-MVL) circuits. The proposed structure, which is more area and power efficient than state-of-the-art fault tolerant adders, is able to detect all single and multi-bit unidirectional faults. The efficiency of the proposed fault tolerant adder is evaluated by comparing its characteristics to those of two state-of-the-art fault detection schemes in adders as well as the conventional duplex and parity bit checkers in a 90 nm technology. The results reveal that the proposed 64-bit Berger code checker for adders imposes up to 6.7% and 27.2% delay and area penalties, respectively with a cost of static power dissipation. In the proposed scheme, in sub threshold regime, the power penalty is just 1%, while its area overhead is only 31%. The drawback of using this scheme in sub threshold regime is that delay time introduced to the circuit is unacceptable. So, depending on the application, we should choose one of the above-mentioned schemes.

An Efficient Current Mode MVL Residue Code Checker for Fault-Tolerant Arithmetic

Due to technology scaling, reliability has become one of the biggest challenges in VLSI circuits. A number of techniques have been introduced in the literature, especially for arithmetic and logic unit in computers. One of well-known schemes for fault-tolerant arithmetic is the use of arithmetic residue codes. A key problem with most of the previous works regarding residue-based checker is that these methods impose an unacceptable area penalty. In this paper, we propose a novel residue checker with current mode multi-valued logic (CMMVL). A plain design procedure with arbitrary modulo is introduced; also a more efficient integrated scheme for modulo 3 has been demonstrated. The results of the plain CMMVL scheme showed up to 19.5% and 42.9% lower delay and power consumption, respectively, compared with those of the conventional CMOS. Also, utilizing the integrated CMMVL provided, on average, about 17.7% and 80.2% lower delay and power consumption, respectively.

Signed higher-radix full-adder algorithm and implementation with current-mode multi-valued logic circuits

A novel algorithm for full-addition of two signed, higher-radix numbers is proposed and implemented by combining multi-valued logic min, max, literal and cyclic operators. Owing to disjoint terms involved, multi-valued logic min and max operators are replaced with ordinary transmission operation and sum, respectively. A multi-valued logic cyclic gate is designed by using a current-mode threshold circuit while the literal is realised by only voltage-mode switching circuits. The threshold circuit employed within the cyclic gate exhibits improved dynamic behaviour compared to its previous counterparts employing voltage-mode binary logic switching circuits. It also allows much higher radices compared to previous current-mode threshold circuits owing to its superior mismatch properties. Thus, the cyclic gate achieves a superior performance compared to its predecessors. As a direct extension to cyclic operation in radix-8, a resultant single-digit, radix-8 full-adder and its 3-bit counterpart voltage-mode circuits are designed and their performance compared. It is shown that the developed signed addition algorithm can be realised by using the proposed full-adder. Finally, the algorithm is also exploited for a multi-digit case. Simulation results demonstrate that proposed architectures can be used in high-performance arithmetic units.

Implementation of Multi-Valued Logic Gates Using Full Current-Mode CMOS Circuits

In this paper, a novel multi-valued logic gate set is designed by using only current-mode CMOS circuits. The gate set consists of min, max, inverter, literal, and cyclic operators based on a current-mode, versatile, novel threshold topology. They are shown to exhibit better static and dynamic behavior and consume less area compared to previous MVL design topologies and binary-logic counterparts. The gate circuits are investigated in terms of analog design aspects, such as mismatch and noise. The proposed topology is compared to previous topologies in terms of attainable radix and DC characteristics. A radix-8 multiplex function and a radix-8 full-adder circuit is designed to demonstrate the advantages of new current-mode multi-valued logic circuits.