Pass Transistor Logic Research Articles

Design and Implementation of PLL with Dead Zone-Less Low-Power Phase Frequency Detector

This project introduces a Phase-Frequency Detector (PFD) that includes a dedicated circuit for removing the dead zone. This design utilizes Pass Transistor Logic (PTL) and Delay Cells (DCs) to effectively address this issue. Additionally, a Low-Pass Filter is integrated into the system and connected with charge pump, employing a technique that replaces resistors with transistors, thereby significantly reducing the overall circuit area. Furthermore, a Phase-Locked Loop (PLL) serves to eliminate the dead zone and significantly reduce the circuit's size. This project aims to advance circuit design methodologies by enhancing performance and minimizing area requirements.

A comprehensive analysis of ultra low power GNRFET based 20T hybrid full adder for computing applications

In an era where energy efficiency is as important as computational speed, this paper introduces a new full adder circuit design that effectively integrates dynamic power gathering (DPG) power conservation benefits with XOR-XNOR pass-transistor logic (PTL) area and performance efficiencies using graphene nanoribbon field-effect transistors. GNRFETs are useful for digital logic due to their high carrier mobility and tunable bandgap. The paper describes the circuit’s seamless transition full adder response, demonstrating the tri-mode dynamic power gating strategy capacity to reduce static power depletion. The proposed hybrid full adder performs well with 7.76 nW power consumption, 481 ps latency, and 3.73 aJ PDP. This reduces power consumption by 99.9%, delay by 99.0%, and PDP by 99.8% compared to other adders. The effects of temperature, voltage, Noise immunity and Carry Forward Adders integration on power, delay, and PDP are also analysed, proving the design’s robustness. The adaptability of our full adder architecture allows its implementation in more complicated arithmetic and logic units, indicating a scalable and energy-efficient paradigm for future integrated circuits.

Design of low delay low power hybrid logic based flip-flop using FinFET

The need for a low-power and high-speed technology for computation of digital signals is rising due to the fast growth of technological innovations. Flip-flops serve as fundamental elements in signal processing technologies. Hybrid logic has great potential for constructing flip-flop circuits because of its minimal transistor count as well as low-power properties.The present investigation presents a design for a tiny and low-power hybrid flip-flop that operates fully statically. The design has been developed by utilizing different circuitry-reduction techniques. It incorporates a hybrid logic approach combining pass transistor logic to decrease circuit complexity. The ongoing work utilizes a hybrid logic with low delay and low power to generate flip-flops. The proposed flip-flop design significantly decreases latency compared to the existing master-slave flip-flops. This flip-flop remains immune to clock overloading, resulting in reduced power consumption. Reducing the quantity of PFET (P-channel Field Effect Transistor) transistors enhances the circuit's delay, area, and power consumption. Implementing these circuit optimization techniques yields several benefits, such as reduced CLOCK-to-OUT and DIN-to-OUT node delays, decreased average power consumption, lower leakage power, and a transistor count of only 18. The results were achieved using Cadence Virtuoso at 18 nm finFET technology, with varied process corners, supply voltages ranging from 0.7 V to 1 V, and temperatures ranging from -50 °C to 75 °C. This study also presents a Monte Carlo simulation of power consumption, leakage, and delay for the suggested flip-flop. According to the simulations, the recommended flip-flop exhibits exceptional stability. The recommended flip-flop has lower power usage by at least 17.95 % compared to standard architectures due to the lower number of PFET transistors.

High-performance and low-power decoder circuits for SRAMs using mixed-logic scheme

A mixed-logic design scheme utilizing pass-transistor logic (PTL) and dual-value logic (DVL) in combination with static CMOS logic for decoders in SRAMs is proposed. By using of the mixed-logic circuit, new n-Transistor (T) NAND/AND structures were provided for decoders, while achieving fewer transistors, faster speed, lower power dissipation as compared to traditional circuits, and having full-swing capability and good noise immunity. Experiments were conducted using TSMC 28 nm process for mixed-logic decoders, and the results show the superiority in terms of propagation delay and power dissipation, compared to the conventional corresponding circuits. A mixed-logic 2-4 decoder exhibits 36 % reduction in propagation delay and 10 % improvement in power dissipation; A mixed-logic 3-8 decoder exhibits 27 % reduction in propagation delay and 5.5 % improvement in power dissipation; While, A mixed-logic 4-16 decoder exhibits 30 % reduction in propagation delay and 5 % improvement in power dissipation; As well, A mixed-logic 5-32 decoder exhibits 34 % reduction in propagation delay and 6.3 % improvement in power dissipation.

Efficient 32-nm CNTFET-Based 1-Bit Adder: A Fast and Energy-Optimized Design

CNTFETs are a shows potential choice for traditional CMOS technology due to their potential for lesser power consumption and superior performance. In the present paper, a new 1-bit hybrid full adder has been deliberated and proposed using both pass transistor (PT) and transmission gate logics (TGL), which utilizes a total of 16 transistors. The combination of PT and TGL can lead to improved power efficiency, reduced delay, and enhanced circuit performance in various VLSI applications. For 0.9 V supply voltage at 32-nm CNTFET technology, the power consumption is 0.0748 μW, which is to be an exceptionally low value with a lesser delay of 7.586 Ps and the power-delay-product (PDP) of 0.5674 aJ. The results obtained from this analysis demonstrate the power efficiency, speed, and overall performance of the proposed full adder design. The combination of 32-nm CNTFET technology, deliberate circuit design choices, and the use of specific logic elements (CMOS inverters and strong transmission gates) contributes to the reported characteristics. Using a 0.9 V supply voltage and 32-nm Stanford CNTFET Model technology, the suggested 1-bit adder circuit's concert was investigated using the Mentor Graphics Tool. Finally, using the proposed 1-bit full adder circuit, an N-bit ripple carry adder (N=8, 16 & 32) is implemented and demonstrated. The Simulation results of the 8-bit RCA with a power consumption of 0.373 μW, the delay is 16.852 Ps and the PDP is 6.2857 aJ. These results show that proposed RCA’s have better performance compared to the already reported designs in terms of performance, speed, and power economy.

Design of a High-Speed, Low-Power PTL-CMOS Hybrid Multiplier Using Critical-Path Evaluation Model

The multiplier is the fundamental component of many computing modules. As the most important component of a multiplier, the full adder (FA) also has a significant impact on the overall performance. Full adders based on pass transistor logic (PTL) have been a very popular research field in recent years, but the uneven delay makes it difficult to analyze the critical path of multipliers based on PTL full adders. In this paper, we propose a model to evaluate the critical path of the carry save array (CSA) multiplier that could reduce the size of the simulation input set from 4 G to 93 K to finally obtain the maximum delay of the multiplier. We propose a novel low-power, high-speed CSA multiplier based on both PTL full adders and CMOS full adders, using our critical-path evaluation model. The proposed work is implemented in the 28 nm process. We use the model to reduce the worst-case delay by 14.5%. The proposed multiplier improved the power delay product by 9.4% over the conventional full CMOS multiplier.

CMOS full adder cells based on modified full swing restored complementary pass transistor logic for energy efficient high speed arithmetic applications

In modern Digital System design, adders are widely used in many applications including Microprocessors, Digital Signal Processors, Arithmetic Logic Units and digital signal processing. Power efficiency is an important key factor for any integrated circuits. By considering the importance of Full Adder (FA) cells, their power consumption may play significant role in overall power consumption. So designing a low-power full adder is important to achieve the high-performance computing. Swing restored technique is commonly used method to reduce the signal swing at the internal nodes and it helps to reduce the power consumption and improves the circuit's speed. This paper presents a novel hybrid full adder cell design using the modified swing restored technique and complementary pass transistor logic. The Full Adder circuit was implemented using Cadence Virtuoso tool on gptk 180nm CMOS process technology. The proposed full adder was compared with earlier reported circuits based on Delay, Power and PDP. The comparison shows that proposed circuit consumes less power with high performance. Also various process corners and noise immunity were analyzed to find the sensitivity of the circuit. Further an 8-bit Ripple Carry Adder was designed using the proposed full adder to verify the functionality in higher order bits. Simulations were performed and analysed using the Cadence Spectre.

Implementation and Analysis of CMOS and Pass Transistor Logic Based Full Adder Circuits

Abstract: In electronic industry the level of integration is an important aspect as it makes the electronic device simpler and more reliable. The device density increases with the better level of integration. Power dissipation, Area occupied and Propagation delay are some of the important factors that need to be considered. These parameters play a vital role in manufacturing portable electronic gadgets. Many binary adders are formed using full adders. Hence, if any enhancements have to be made to improve the performance, it can be made at the root level i.e., adders circuits itself. This in turn helps in bettering the performance of the electronics circuits which follow adder circuits. The low power VLSI design is of great importance due to portable electronic products. Full adder is a type of adder circuit that adds three inputs and gives two outputs. Out of three, two will be the present inputs and the third input will be the carry from the previous stage. ‘A’ and ‘B’ are the actual inputs, ‘C’ is the carry from the previous operation. SUM and CARRY OUT are the two outputs. In this work, Design and Implementation of full adder using conventional CMOS design and Pass Transistor Logic based Full adder circuits are carried out. At last comparison is made between the two designs with respect to power dissipation, delay and area (number of transistors). Cadence Virtuoso Tool is used in design and simulation conventional CMOS design and Pass Transistor Logic based Full adder circuits. The entire work is simulated in 180nm CMOS technology.

A 6-bit absolute value detector based on MOSFET and PTL structure

As science and technology develop fast, people nowadays can have an easy approach to various advanced products. The use of Internet of Things has become a reality. To ensure its reliable implementation in daily life, stable and efficient hardware equipment like sensor is essential, where absolute value detector is widely used. A detector is created on the basis of this. The circuit can compare a signed 6-bit number with the threshold of a 5-bit number. This design uses MOS and pass-transistor logic (PLT) structure as the basic parts to form the transcoding logic and the subtraction logic. This paper also discusses the optimization of its minimum latency and energy usage based on logic effort parameters. In order to match a sequence of minimum delays, the article gives various power supply voltages and calculates each schemes lowest energy consumption for each voltage. The reduction of the energy cost is significant, which means the circuit has application value in reality. Besides, the different results are listed in a scatterplot to find out the trend of optimization, which may be helpful for selecting a proper scheme in the real program.

Design and optimization of phase frequency detector through Taguchi and ANOVA statistical techniques for fast settling low power frequency synthesizer

In this work, a novel phase frequency detector (PFD) architecture using pass transistor logic is proposed. The circuit does not have a reset path, resulting in the elimination of blind zone and dead zone. The ϕ-V characteristics of the PFD were found to have better linearity across the range of −π to π due to the absence of blind and dead zones. The Taguchi and ANOVA statistical techniques were used to optimize the PFD. The optimized PFD exhibited a phase noise of −142.24 dBc/Hz, consumed 5.64 μW of power and had a maximum operating frequency of 5.25 GHz, and a delay of 10.65 ps. Using this PFD, a GHz-range synthesizer was designed, and its performance characteristics were obtained from circuit simulations using CADENCE Virtuoso. The synthesizer had a power consumption of 4.25 mW at a supply of 1.8 V, achieved a lock time of 2.95μs, and could generate frequencies ranging from 0.1 GHz to 4.75 GHz while occupying a chip area of 0.013 mm2. Moreover, the work introduced a new figure of merit, FoM. The synthesizer has potential applications in various devices such as radio receivers, televisions, mobile phones, satellite receivers, and GPS systems.

Performance Analysis of Hybrid Comparator using 45nm Technology

In the present real-time world, due to the improvements and innovations of System on Chip (SoC) applications, there is a requirement to integrate multiple technology design topologies. The electronic system design is classified as analog, digital, and mixed-signal design. The comparator is the major building block used in the datapath of System on Chip (SoC) application device. The usage of these devices depends on not only functionality but also on the non-functionality parameters considering different performance estimation metrics. The nonfunctional performance metrics for a transistor level design depends on the number of transistors, switching activities of logic level voltages and delay between input and outputs. These performance metrics are improved by considering the multiple logic families for multiple output generations instead of using a single logic family topology. The comparator is the major component in the arithmetic circuits for SoC applications and can be realized by using various design topologies. The vividly used topologies are Conventional CMOS logic, Pass Transistor Logic (PTL), Gate Diffusion Input (GDI) Logic, Stacking technique, Quantum-dot cellular automata, etc. The selection of the design topology for the comparator is made based on the non-functional parameters. The performance of non-functional parameters is improved by combining the topology architectures of different design techniques. In this paper, the comparator is designed using conventional CMOS logic, PTL, GDI, and a hybridized topology for best performance and the same is implemented using 45nm technology. These circuits are designed by using Cadence Virtuoso Electronic Design Automation (EDA) design tools. Non-functional performance parameters are analyzed for different topologies. Index Terms: VLSI Design, Comparator, Datapath, EDA tools, CMOS Logic, GDI Logic, PTL Logic.

WITHDRAWN: Design of a novel 1-bit full adder with hybrid logic for full-swing, area-efficiency, and high-speed

In this paper, we propose a hybrid full-swing adder (HFSA) circuit that uses the hybrid full-swing logic (HFSL) technique, which consists of 20 transistors. This circuit relies heavily on a 12-transistor XOR-XNOR circuit to optimize the area and power. Our novel XOR-XNOR circuit plays a crucial role in achieving high-efficiency HFSA circuits. It integrates 2-to-1 multiplexers, pass transistor logic, and inverters to deliver glitch-free full-swing outputs. We compared the efficiency and practicality of our design with those of 10 alternatives by considering their performances and characteristics. Our novel XOR-XNOR circuit surpassed its counterparts with an exceptional chip area reduction of 14.14–28.01 %, an average power of 2.44 μW, and remarkably low delays of 25.88 and 24.87 ps. Notably, the proposed full adder achieved a chip area reduction of 11.30–49.69 %, 3.582 μW power, and a 72.66 ps delay. It emphasizes large-scale structures, such as 4-bit to 64-bit full adders, implemented using cascaded designs with a novel ripple carry adder. Using multipoint and Monte Carlo analysis in the ADEXL design suite to ensure the reliability of all circuits using the Cadence Virtuoso with the GPDK45 nm technology. The proposed method is an alternative to high-speed electronic systems with potential benefits.

Analysis Of 4-Bit Absolute Value Detector for ECG Signal Comparation

In the present era, where numerous heart conditions are prevalent, the significance of monitoring cardiac electrical signals has surged within the medical realm. Within this study, we leverage Complementary Metal Oxide Semiconductor (CMOS) and Pass-transistor Logic (PTL) methodologies for crafting and refining a 4-bit absolute value detection mechanism. This mechanism serves to identify and juxtapose electrocardiogram (ECG) signals. The 4-bit absolute value detection system is bifurcated into two core segments: one for absolute value identification and the other for comparative analysis. This setup facilitates a binary input's comparison with a predetermined threshold, thereby yielding a corresponding comparative outcome. Subsequently, a meticulous assessment is conducted on the lengthiest pathway, which is then subject to refinement through gate sizing and voltage supply (Vdd) adjustments. The findings unveil a delay of 34.13tp0 and an energy dissipation of 184.832 C. The resultant 4-bit absolute value detection mechanism, borne from this research institution's efforts, emerges as an invaluable asset in the medical domain, attributed to its exceptional optimization with respect to minimal delay and energy outlay.

Area and power efficient divide-by-32/33 dual-modulus pre-scaler using split-path TSPC with AVLS for frequency divider

Abstract Pre-scalers are electronic circuits used in phase-locked loops to multiply frequencies. This is achieved by dividing the high-frequency signals generated from a voltage-controlled oscillator. The high-frequency operation of pre-scaler circuits leads to significantly higher power consumption. To address this, D flip-flops (D-FF) realized using true-single phase clocking (TSPC) logic. The work suggests incorporating the Adaptive Voltage Level Source (AVLS) circuit with the Dual Modulus Pre-Scaler (DMPS) circuit to reduce power consumption. In addition to the incorporation of the AVLS circuit, pass transistor logic (PTL) used in the feedback, further minimizes transistors and power. This paper proposes three different designs for divide-by-32/33 DMPS circuit. The proposed-1 design combines regular TSPC-based D-FF with PTL in the feedback and an AVLS circuit, resulting in an average power reduction of 36.5%. The proposed-2 design employs split-path TSPC-based D-FF with logic gates and an AVLS circuit, achieving a power reduction of 46.9%. The proposed-3 design employs split-path TSPC-based D-FF with PTL in the feedback and an AVLS circuit, achieving a significant power reduction of 47.8% compared to the existing DMPS circuit and transistor count by 9.1%. The proposed circuits are realized using a CMOS 180 nm technology node. Cadence Virtuoso and Spectre tools are used. The proposed divide-by-32/33 DMPS circuits also realized in the CMOS 45 nm technology node to verify the functionality in the lower technology node. A power reduction of 46.86% observed when compared to the reference circuit. The proposed designs are both power- and area-efficient, making them promising solutions for minimizing power consumption in pre-scaler circuits.

Simulation and Characterization of Carbon Nanotube-based 2:1 Multiplexer Electrical Properties

This paper reports on using simulation to characterize a Carbon Nanotube (CNT) based 2:1 multiplexer (MUX). This study aimed to evaluate the electrical properties, particularly the propagation delay, average power consumption, Power-Delay Product (PDP), and Energy-Delay Product (EDP). Different design approaches namely conventional CMOS, Pass Transistor Logic (PTL) approach, and Gate Diffusion Input (GDI) were adopted. The voltage supply (VDD) and diameter of the CNT are varied to see the effect on the electrical properties. The simulation was carried out using HSPICE. Through simulation, it is found that the GDI approach used the least number of transistors followed by PTL and CMOS. The calculation of the propagation delay exhibits a substantial improvement of more than 95% using the GDI approach. The average power consumption shows a 55.30% and 35.16% reduction when compared to CMOS and PTL respectively. The PDP demonstrates an improvement of more than 95% when compared with conventional CMOS and PTL approaches. The same trend of observation is also achieved for EDP. The variation of the VDD and chirality has a markable effect on the propagation delay and average power consumption. This is a preliminary attempt to evaluate the performance of CNT implementation in MUX. The outcome can become the guideline for engineers working in circuit design using emerging materials for future nanoelectronics applications.

Novel Design of Ripple Carry Adder using High Speed 12T Hybrid MOS Transistors

This paper designs and extends a high speed full adder using 12 MOS Transistors to a ripple carry adder (RCA). The proposed design reduces delay and is effective for Power Delay Product (PDP). Using both complementary MOSFET (CMOS) logic and complementary pass transistor logic(CPL), a new 6T XNOR full adder(FA) is created. CPL is used in the design for Carry and Sum logic in order to minimise circuit delay. The proposed work has a delay of 11.86 ps and a PDP of 0.368fj. By using a newly proposed single bit adder, a 4-bit Ripple Carry Adder(RCA) is designed with 1.2 v supply yielding a power of 572.063uw, delay 0.32ns and PDP 183.06 fj. The outcomes obtained are compared with existing models. For characterstics of speed and PDP, the proposed model outperforms existing models significantly. The circuit was designed in 90nm GPDK technology by using the CADENCE VIRTUOSO TOOL.

Low power, less area, and highly efficient hybrid 1-bit full adder

The widely used and efficient technique is to design an FA circuit using XNOR-XOR cells in the Pass transistor and CMOS hybrid logic. The performance metrics of hybrid full adders, such as power, driving capability, and power, depend highly on the XNOR-XOR circuit. The proposed FA design provides optimization with respect to speed and performance. Low load capacitance and low static power dissipation in the circuit enabled the optimized design characteristics. The proposed circuits outperform existing designs in device parameters such as device speed, total energy consumption, power, and fanout. Cadence Virtuoso is the simulation tool used for simulations and results with a 90nm model. The test outcomes show the new design outperforms other FA designs regarding speed and power. In comparison to the available FA modules, the proposed FA reduces delay by 48% and improves power and power delay products by 7% and 52%, respectively. Microwind design software is used to create layouts. The paper presents a more straightforward layout of the proposed design that takes up less area.

Design of Low Power 64-Bit Hybrid Full Adder

Abstract: In the realm of Computer Science, integrated circuits (ICs) have propelled microprocessor and digital signal processor development, hinging on the 1-bit full adder's significance for mathematical tasks. To amplify overall efficiency, enhancing this adder is pivotal. As demand surges for power-efficient devices like smartphones and MP3 players, maintaining a balance between speed, size, and power usage becomes imperative. Engineers tackle this challenge while bridging battery technology gaps. We propose advanced 1-bit full adder designs, evaluated via Cadence Virtuoso. A hybrid version merges Pass-Transistor Logic (PTL), Transmission Gates (TGs), and static CMOS logic. An optimized alternative incorporates efficient 3T-XOR logic. The comparative study considers crucial metrics: the existing FA’s 8.83µW power vs. the proposed's 8.49µW; the proposed's shorter delay of 64.53ps vs. the existing FA’s 83.1ps (18 vs. 22 transistors). At 64 bits, the existing FA’s consumes 66.8µW with a 470.94ps delay (1408 transistors), while the proposed maintains 35.05µW, 64.53ps, and fewer transistors (1152). In summary, the proposed adder excels in efficiency, delay, and transistor use for energy-efficient arithmetic operations.

Low-Power Pass-Transistor Logic-Based Full Adder and 8-Bit Multiplier

With the rapid development of information technology, the demand for high-speed and low-power technology for digital signal processing is increasing. Full adders and multipliers are the basic components of signal processing technology. Pass-transistor logic is a promising method for implementing full adder and multiplier circuits due to the low count of transistors and low-power characteristics. In this paper, we present a novel full adder based on pass transistors. The proposed full adder consists of 18 transistors. The post-layout simulation shows a 13.78% of power reduction compared to conventional CMOS full adders. Moreover, we propose an 8-bit signed multiplier based on the proposed full adder. The post-layout simulation shows an 8% power reduction compared to the multiplier produced by the Design Compiler synthesis tool. Compared to the existing work with a similar process, our work achieved only 19.02% of the power-delay product and 3.5% of the area-power product.

ALUSGDI: Low power arithmetic logic unit based sliced processor using GDI and MGDI

In recent years, many digital logic circuits in terms of transistors such as Pass Transistor Logic (PTL), Complementary Metal Oxide Semiconductor (CMOS) logic and etc. have been used for implementing DSP algorithms. Gated Diffusion Input (GDI) logic is also another method for implementing digital circuits. In this work, GDI logic style is used in the proposed ALU based Filter Bank. The ALU unit of the proposed filter bank is designed by modified GDI logic. Power consumption of the entire design is also reasonably reduced using recursive parallel self-timed adder. GDI logic has three terminals which are Common Gate (G), PMOS (P)/NMOS (N) and output terminal. The number of transistors is reduced when compared to Complementary Metal Oxide Semiconductor (CMOS) logic. Hence, the reduced number of transistors eliminates the switching activity and power dissipation. The GDI logic consumes 65% less area and 91.4% less power when compared to CMOS logic. The modified GDI logic provides 77.5% area reduction when compared to CMOS logic. The experimental results obtained using the proposed ALU based Sliced Processor by employing GDI logic compared with the traditional filter bank techniques. ALU based filter bank design speeds up significantly through GDI concepts when compared to the interpolated filter bank and the design is implemented in 65 nm CMOS technology.