DOCSLIB.ORG

Logic Styles with Mosfets

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Logic Styles with Mosfets Logic Styles with MOSFETs NMOS Logic One way of using MOSFET transistors to produce logic circuits uses only n-type (n-p-n) transistors, and this style is called NMOS logic (N for n-type transistors). An inverter circuit in NMOS is shown in the figure with n-p-n transistors replacing both the switch and the resistor of the inverter circuit examined earlier. The lower transistor in the circuit operates as a switch exactly as the idealised switch in the original circuit: with 5V on the Gate input, the conducting channel is created in the transistor and the “switch” is closed; with 0V on the Gate there is no channel and the transistor is non-conducting - the “switch” is open. The depletion mode transistor is produced by adding a small amount of donor material to the The upper transistor, called a depletion mode channel region of a n-p-n transistor, so that there are a small number of free electrons in the channel transistor, operates as a resistor to limit current even when there is no electric field across the flow when the “switch” is closed. This transistor is insulator. This provides a connection through the a modified n-p-n transistor that always has a transistor for all Gate voltages. The conductivity of channel present and is always conducting, although the channel is lowest (Resistance is highest) when the conductivity is low when there is 0V on the the Gate is at 0V. When the Gate is at 5V and more Gate and higher when 5V is on the Gate: see Box. free electrons are pulled into the channel by the electric field, the conductivity is highest (Resistance The function of this transistor is purely resistive is lowest). The transistor acts a variable Resistance. and is present, as in the earlier circuit, to restrict This is quite useful in NMOS circuits as when there is current flow through the circuit and the output current flow and limit power consumption in the voltage is at 0V, the resistance of the depletion circuit. A transistor is used as a resistor because mode transistor is highest limiting the current flow. the space taken up on the substrate is much less When the circuit is opened and the output voltage than with other methods of producing resistors on starts rising to 5V, the resistance decreases allowing silicon. a more rapid switching of the output to 5V. An NMOS NAND circuit is shown in the figure to the right. Again n-p-n transistors are used to replace the ideal switches of the earlier circuit, while a depletion mode n-p-n transistor replaces the resistor. It operates in exactly the same way as the earlier circuit. NMOS circuits suffer the same faults as our earlier circuits but have an extra electrical problem as well. The problems seen are:- • continuous power consumption when a circuit is made through the logic and a current flows. • Asynchronous switching times as it is quicker to switch the output from 5V→0V → than from 0V 5V (see earlier explanation) • the new electrical problem is that the switch transistors have a small resistance, so that when a current flows there is a small voltage drop across the switch transistors and the output voltage does not quite reach 0V. This causes problems when there are large collections of interconnected circuits, and extra circuitry has to be added to restore the voltage to 0V. A large number of circuits can be placed on a single piece of silicon and interconnected to produce complex circuits. NMOS logic was used extensively in the 1970s and early 1980s for most digital semi-conductor devices, “chips”, e.g. the Intel 8086 and Motorola 68000 microprocessors. 17 CMOS Logic Most modern chips use CMOS logic, as it has many advantages over NMOS: there were operational problems with CMOS in the past that caused NMOS logic to be used for many years. In CMOS circuits both n-p-n and p-n-p MOSFET transistors are used with circuits structured into 2 parts. One part consisting of purely n-p-n transistors controls the connection of the output of the circuit to the 0V power supply terminal, i.e. it sets the output to a ‘0’, while the other part consisting of purely p-n-p transistors controls the connection of the output to the 5V power supply terminal, i.e. it sets the output to a ‘1’. This can be seen in the figure to the right which shows a CMOS inverter circuit. CMOS stands for Complementary MOS. The Complementary comes from the operation of the circuit parts such that only one part makes a connection between the output and the power supply at any time: the n-p-n part or the p-n-p part. There must never be an arrangement when the output has a good connection to both power supply terminals as then a short-circuit condition exists and the circuit will be damaged. In the inverter, the input controls both the upper p-n-p transistor and the lower n-p-n transistor. With 5V on the input the lower transistor conducts, but not the upper, and the output is at 0V; with 0V on the input the upper transistor conducts, but not the lower, and the output is 5V. Either the upper or lower circuit connects the output to a power supply terminal, but there is never a good connection to both. The figure to the left shows the 2 possible configurations of the inverter with switches replacing the transistors: the circle on the input to the upper switches indicates that the switch is closed when 0V is on the switch control. The figure on the next page shows the CMOS logic for the 2-input NOR gate. It has 2 n-p-n and 2 p- n-p transistors. The circuit outputs 5V only when both p-n-p transistors are conducting, i.e. when both inputs are 0V. At all other times one of the inputs is at 5V, one of the n-p-n transistors is conducting, and at most one of the p-n-p transistors, but not both, so that the output is at 0V. The different configurations of the NOR circuit can be seen in the switch diagrams in the figure. Again, there is never a constant current flow through the circuit and never a short-circuit. Examining the lower part of the circuit (at the bottom of the figure), the output is at ‘0’ if input A is ‘1’ or input B is ‘1’ - the NOR function. For the upper part of the circuit the output is at ‘1’ if both input A is ‘0’ and input B is ‘0’ - this function is NOT(A) AND NOT(B). Of course this function is, by deMorgan’s Rule, just the NOR of A and B. Thus both the upper and lower parts perform the NOR function: the upper part gives the 1s in the NOR truth table, the lower part the 0s. CMOS circuits are much better than their NMOS equivalents:- • For no set of inputs is there a circuit through the transistors connecting the power supply terminals, so that there is no continuous current flow and no continuous power consumption. However, as is set out below, there is some power consumption when the circuit configuration is changing. • the transistors can be made to provide symmetric switching times for both output transitions: 5V→0V and 0V→5V. This makes CMOS logic faster than the equivalent NMOS circuit as the latter has a longer 0V→5V switching time. • Since there are no constant current flows, there are no voltage drops across the transistors and CMOS circuits output full 5V and 0V signals. • There is always a good connection between the output and the power supply: in NMOS there is a resistive connection to 5V. The last 2 points make building large circuits much easier than for NMOS: it is just a matter of plugging CMOS circuits together, although there are times when more complex circuits provide faster and/or smaller solutions. It should be noted that there are many ways to put n-p-n and p-n-p transistors together that do not produce CMOS circuits, i.e. circuits without complementary action. 18 Power Consumption in CMOS circuits This arrives from 2 effects, which can be examined by considering the inverter circuit with its input at 0V and its output at 5V. When the input is changed to 5V both transistors start to change, the upper to a non-conducting state and the lower to a conducting state, and electrons start to move through the lower transistor from 0V to the output which is still at 5V. Since they move across a voltage drop power is consumed, until enough electrons arrive at the output to reduce its voltage to 0V. There is a similar effect on switching the input from 5V to 0V: the output changes from 0V to 5V, but this time it is the electrons moving through the voltage drop across the upper transistor that causes the power consumption, until enough positive charge has built up at the output for it to be at 5V. The amount of energy consumed is determined by the number of electrons that have to cross to or from the output to change the voltage to 0V or 5V respectively. The number of electrons in each case is the same and is 19 controlled by the capacitance of the output (capacitance of a body is the amount of charge required to change its voltage by 1 Volt), which is controlled by structural factors.
Load more

Recommended publications
  • Role of Mosfets Transconductance Parameters and Threshold Voltage in CMOS Inverter Behavior in DC Mode
    Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 28 July 2017 doi:10.20944/preprints201707.0084.v1 Article Role of MOSFETs Transconductance Parameters and Threshold Voltage in CMOS Inverter Behavior in DC Mode Milaim Zabeli1, Nebi Caka2, Myzafere Limani2 and Qamil Kabashi1,* 1 Department of Engineering Informatics, Faculty of Mechanical and Computer Engineering ([email protected]) 2 Department of Electronics, Faculty of Electrical and Computer Engineering ([email protected], [email protected]) * Correspondence: [email protected]; Tel.: +377-44-244-630 Abstract: The objective of this paper is to research the impact of electrical and physical parameters that characterize the complementary MOSFET transistors (NMOS and PMOS transistors) in the CMOS inverter for static mode of operation. In addition to this, the paper also aims at exploring the directives that are to be followed during the design phase of the CMOS inverters that enable designers to design the CMOS inverters with the best possible performance, depending on operation conditions. The CMOS inverter designed with the best possible features also enables the designing of the CMOS logic circuits with the best possible performance, according to the operation conditions and designers’ requirements. Keywords: CMOS inverter; NMOS transistor; PMOS transistor; voltage transfer characteristic (VTC), threshold voltage; voltage critical value; noise margins; NMOS transconductance parameter; PMOS transconductance parameter 1. Introduction CMOS logic circuits represent the family of logic circuits which are the most popular technology for the implementation of digital circuits, or digital systems. The small dimensions, low power of dissipation and ease of fabrication enable extremely high levels of integration (or circuits packing densities) in digital systems [1-5].
    [Show full text]
  • MOSFET - Wikipedia, the Free Encyclopedia
    MOSFET - Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/MOSFET MOSFET From Wikipedia, the free encyclopedia The metal-oxide-semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET), is by far the most common field-effect transistor in both digital and analog circuits. The MOSFET is composed of a channel of n-type or p-type semiconductor material (see article on semiconductor devices), and is accordingly called an NMOSFET or a PMOSFET (also commonly nMOSFET, pMOSFET, NMOS FET, PMOS FET, nMOS FET, pMOS FET). The 'metal' in the name (for transistors upto the 65 nanometer technology node) is an anachronism from early chips in which the gates were metal; They use polysilicon gates. IGFET is a related, more general term meaning insulated-gate field-effect transistor, and is almost synonymous with "MOSFET", though it can refer to FETs with a gate insulator that is not oxide. Some prefer to use "IGFET" when referring to devices with polysilicon gates, but most still call them MOSFETs. With the new generation of high-k technology that Intel and IBM have announced [1] (http://www.intel.com/technology/silicon/45nm_technology.htm) , metal gates in conjunction with the a high-k dielectric material replacing the silicon dioxide are making a comeback replacing the polysilicon. Usually the semiconductor of choice is silicon, but some chip manufacturers, most notably IBM, have begun to use a mixture of silicon and germanium (SiGe) in MOSFET channels. Unfortunately, many semiconductors with better electrical properties than silicon, such as gallium arsenide, do not form good gate oxides and thus are not suitable for MOSFETs.
    [Show full text]
  • Vlsi Design Lecture Notes B.Tech (Iv Year – I Sem) (2018-19)
    VLSI DESIGN LECTURE NOTES B.TECH (IV YEAR – I SEM) (2018-19) Prepared by Dr. V.M. Senthilkumar, Professor/ECE & Ms.M.Anusha, AP/ECE Department of Electronics and Communication Engineering MALLA REDDY COLLEGE OF ENGINEERING & TECHNOLOGY (Autonomous Institution – UGC, Govt. of India) Recognized under 2(f) and 12 (B) of UGC ACT 1956 (Affiliated to JNTUH, Hyderabad, Approved by AICTE - Accredited by NBA & NAAC – ‘A’ Grade - ISO 9001:2015 Certified) Maisammaguda, Dhulapally (Post Via. Kompally), Secunderabad – 500100, Telangana State, India Unit -1 IC Technologies, MOS & Bi CMOS Circuits Unit -1 IC Technologies, MOS & Bi CMOS Circuits UNIT-I IC Technologies Introduction Basic Electrical Properties of MOS and BiCMOS Circuits MOS I - V relationships DS DS PMOS MOS transistor Threshold Voltage - VT figure of NMOS merit-ω0 Transconductance-g , g ; CMOS m ds Pass transistor & NMOS Inverter, Various BiCMOS pull ups, CMOS Inverter Technologies analysis and design Bi-CMOS Inverters Unit -1 IC Technologies, MOS & Bi CMOS Circuits INTRODUCTION TO IC TECHNOLOGY The development of electronics endless with invention of vaccum tubes and associated electronic circuits. This activity termed as vaccum tube electronics, afterward the evolution of solid state devices and consequent development of integrated circuits are responsible for the present status of communication, computing and instrumentation. • The first vaccum tube diode was invented by john ambrase Fleming in 1904. • The vaccum triode was invented by lee de forest in 1906. Early developments of the Integrated Circuit (IC) go back to 1949. German engineer Werner Jacobi filed a patent for an IC like semiconductor amplifying device showing five transistors on a common substrate in a 2-stage amplifier arrangement.
    [Show full text]
  • Class 08: NMOS, Pseudo-NMOS
    Class 08: NMOS, Pseudo-NMOS Topics: •02 NMOS Logic Gates •03 NMOS Logic Gates •04 Pseudo-NMOS •05 Pseudo-NMOS •06 Transistor Equivalency Dr. Joseph Elias; Dr. Andrew Mason 1 Class 08: NMOS, Pseudo-NMOS NMOS (Martin c. 1) § nMOS Inverter with resistive load § nMOS Inverter with depletion load Depletion nMOS, Vtn < 0 always ON for VGS = 0 § switch level model W/L Q1 > W/L Q2 so Q1 can “pull down” Vout § nMOS NOR gate c = a+b (a) NMOS off (b) NMOS on want to realize resistor with a transistor § nMOS NAND gate § Including transistor resistance c = ab rds º channel resistance RL >> rds so output close to 0V Dr. Joseph Elias; Dr. Andrew Mason 2 Class 08: NMOS, Pseudo-NMOS NMOS (Martin c. 1) • General nMOS schematic Examples: depletion-load nMOS logic – single load transistor – parallel and series nMOS transistor to complete the compliment of the desired function i.e., they determine when the output is low “0” rather than high “1” Dr. Joseph Elias; Dr. Andrew Mason 3 Class 08: NMOS, Pseudo-NMOS Pseudo-NMOS (Martin c. 4) •NMOS Common-Source Amplifier with •Pseudo-NMOS inverter with PMOS load current sourrce load and load capacitor •Choose W/L so that: •Choose Vbias in between VDD and ground Q2 always on since |Vgs| > |Vtp| Q2 in saturation if (for VDD=3.3) |Vds| > |Veff| > |Vgs| – |Vt| VDD – Vout > |Vgs| - |Vt| Vout < VDD - |Vgs| + |Vt| Vout < 1.65 + Vt < 2.45 Q1 in saturation if Vgs = Vin > Vt Vds > Veff > Vgs – Vt => •Current-source realized with a PMOS transistor Vout > Vin - Vt •Power Dissipation: Veff = Vgs - Vt output low (Vin is high): P = IL * VDD Vds = Vgs + Vdg at saturation, Vdg=-Vt output high (Vin is low): P = 0 Valid if: average static dissipation: P = ½ * IL * VDD Veff = |Vds-sat| > |Vgs| - |Vtp| -want drain at least Vt from gate Dr.
    [Show full text]
  • Comparative Analysis of Low Power Adiabatic Logic Circuits in DSM Technology
    International Journal of Engineering Trends and Technology (IJETT) – Volume-45 Number3 -March 2017 Comparative Analysis of Low Power Adiabatic Logic Circuits in DSM Technology Shaefali Dixit #1, Ashish Raghuwanshi #2, # PG Student [VLSI], Dept. of ECE, IES college of Eng. Bhopal, RGPV Bhopal, M.P. India Abstract— With the continuous scaling down of dissipation energy loss takes place. While in technology, in the field of integrated circuit design, semiconductor devices, the charge transfer between low power dissipation has become one of the primary different nodes is the process of energy exchange and focus of the research. With the increasing demand for different techniques can be used for minimizing this low power devices adiabatic logic gates proves to be energy loss due to charge transfer. While fully an effective solution. This paper investigates different adiabatic operation is the ideal condition of a circuit adiabatic logic families such as ECRL, 2N-2N2P and operation, in practical cases partial adiabatic operation PFAL. The main aim of this paper is to simulate of circuit is used which gives considerable various logic gates using conventional CMOS and performance. different adiabatic logic families, and thus compare In conventional CMOS circuits the energy stored in for the effectiveness in terms of lower power load capacitors was dissipated to ground. While, dissipation. All simulations are carried out using adiabatic logic, in contrast, offers a way to reuse this HSPICE at 65nm technology with supply voltage is 1V energy and thus prevents the wastage of this energy. at 100MHz frequency, for fair comparison of results By adding the ideas of both the conventional and the W/L ratio of all the circuit is same.
    [Show full text]
  • 3. Implementing Logic in CMOS
    3. Implementing Logic in CMOS Jacob Abraham Department of Electrical and Computer Engineering The University of Texas at Austin VLSI Design Fall 2020 September 3, 2020 ECE Department, University of Texas at Austin Lecture 3. Implementing Logic in CMOS Jacob Abraham, September 3, 2020 1 / 37 Static CMOS Circuits N- and P-channel Networks N- and P-channel networks implement logic functions Each network connected between Output and VDD or VSS Function defines path between the terminals ECE Department, University of Texas at Austin Lecture 3. Implementing Logic in CMOS Jacob Abraham, September 3, 2020 1 / 37 Duality in CMOS Networks Straightforward way of constructing static CMOS circuits is to implement dual N- and P- networks N- and P- networks must implement complementary functions Duality sufficient for correct operation (but not necessary) ECE Department, University of Texas at Austin Lecture 3. Implementing Logic in CMOS Jacob Abraham, September 3, 2020 2 / 37 Constructing Complex Gates Example: F = (A · B) + (C · D) 1 Take uninverted function F = (A · B) + (C · D) and derive N-network 2 Identify AND, OR components: F is OR of AB, CD 3 Make connections of transistors ECE Department, University of Texas at Austin Lecture 3. Implementing Logic in CMOS Jacob Abraham, September 3, 2020 3 / 37 Construction of Complex Gates, Cont'd 4 Construct P-network by taking complement of N-expression (AB + CD), which gives the expression, (A + B) · (C + D) 5 Combine P and N circuits ECE Department, University of Texas at Austin Lecture 3. Implementing Logic in CMOS Jacob Abraham, September 3, 2020 4 / 37 Layout of Complex Gate AND-OR-INVERT (AOI) gate Note: Arbitrary shapes are not allowed in some nanoscale design rules ECE Department, University of Texas at Austin Lecture 3.
    [Show full text]
  • Designing Combinational Logic Gates in Cmos
    CHAPTER 6 DESIGNING COMBINATIONAL LOGIC GATES IN CMOS In-depth discussion of logic families in CMOS—static and dynamic, pass-transistor, nonra- tioed and ratioed logic n Optimizing a logic gate for area, speed, energy, or robustness n Low-power and high-performance circuit-design techniques 6.1 Introduction 6.3.2 Speed and Power Dissipation of Dynamic Logic 6.2 Static CMOS Design 6.3.3 Issues in Dynamic Design 6.2.1 Complementary CMOS 6.3.4 Cascading Dynamic Gates 6.5 Leakage in Low Voltage Systems 6.2.2 Ratioed Logic 6.4 Perspective: How to Choose a Logic Style 6.2.3 Pass-Transistor Logic 6.6 Summary 6.3 Dynamic CMOS Design 6.7 To Probe Further 6.3.1 Dynamic Logic: Basic Principles 6.8 Exercises and Design Problems 197 198 DESIGNING COMBINATIONAL LOGIC GATES IN CMOS Chapter 6 6.1Introduction The design considerations for a simple inverter circuit were presented in the previous chapter. In this chapter, the design of the inverter will be extended to address the synthesis of arbitrary digital gates such as NOR, NAND and XOR. The focus will be on combina- tional logic (or non-regenerative) circuits that have the property that at any point in time, the output of the circuit is related to its current input signals by some Boolean expression (assuming that the transients through the logic gates have settled). No intentional connec- tion between outputs and inputs is present. In another class of circuits, known as sequential or regenerative circuits —to be dis- cussed in a later chapter—, the output is not only a function of the current input data, but also of previous values of the input signals (Figure 6.1).
    [Show full text]
  • Super-Threshold Adiabatic Finfet SRAM with PAL-2N Logic
    Metallurgy and heat treatment of metals Super-Threshold Adiabatic FinFET SRAM with PAL-2N Logic Yuejie Zhang, Jianping Hu, Tianfang Ma, Beibei Qi Faculty of Information Science and Technology, Ningbo University, Ningbo 315211, China Corresponding author is Jianping Hu Abstract With IC process scaling, the leakage consumption has been an important factor in the power consumption of IC chips, which limits the scaling of SRAM. The FinFET device has the advantage in lower leakage current and higher on-state current than the CMOS devices. In this paper, a FinFET SRAM is verified by using adiabatic com- puting. All the circuits of the SRAM except for the storage array are realized by PAL-2N (pass-transistor adiabatic logic with NMOS pull-down configuration) circuits. The storage uses 8T cell that can improve the read margin and keep the write current against the synchronous read/write disturb. All circuits are simulated with HSPICE at a PTM (Predictive Technology Model) 32nm FinFET technology. The results indicated that the energy consumption of the adiabatic FinFET SRAM decreased 49% compared with the SRAM based on CMOS devices. Keywords: SUPER-THRESHOLD, SRAM, ADIABATIC, FINFET, LOW POWER 1. Introduction age current from supply to the ground, and T is oper- The power consumption has been a critical con- ating cycle of the circuits. cern in the VLSI circuit design. Especially the power The adiabatic circuits have advantages compared consumption of embedded SRAM is a significant with the conventional CMOS circuits in low power concern in processors [1]. The SRAM circuits have aspects [5]. The conventional CMOS circuits will large storage density and small access latency, and consume a portion of energy in the form of heat dissi- thus it is used extensively in processors as on-chip pation.
    [Show full text]
  • The Depletion Load.Doc 1/5
    11/19/2004 The Depletion Load.doc 1/5 The Depletion Load Say we connect the gate of a depletion NMOS to its source— we now have a two-terminal device! This device is called a depletion load. Since the depletion load is a two-terminal device, its behavior is defined by the i + relationship between the voltage v across the v device and the current i through it. − For example, a resistor is a two terminal device whose behavior (i.e., its The Depletion Load relationship between i and v) is defined by Ohm’s Law (ivR= ). Although the depletion load is decidedly not a resistor, its i -v relationship does have some similarities with Ohm’s Law. Q: So what is “Ohm’s Law” for a depletion load (i.e., what is ifv= ())? Jim Stiles The Univ. of Kansas Dept. of EECS 11/19/2004 The Depletion Load.doc 2/5 A: A result easily found by implementing our knowledge of depletion MOSFETs! For a depletion load, we find that: iD + iiD = vGS = 0 vDS + vvDS = vGS vGS−VV t=− t − − Q: But since vGS = 0, isn’t the NMOS device in cutoff? A: Nope! Notice that this is a depletion MOSFET, and a depletion MOSFET will conduct when vGS = 0! Thus the MOSFET in a depletion load will always be either in: a) triode or b) saturation. a) Depletion load MOSFET is in triode if: vDS <vVGS− t vV<−0 t vV<−t Jim Stiles The Univ. of Kansas Dept. of EECS 11/19/2004 The Depletion Load.doc 3/5 Therefore, the current will be: =−−⎡ 2 ⎤ iKDDSDS⎣2( vGS Vvv t ) ⎦ =−−⎡⎤2 iK⎣⎦20() Vvvt =−⎡⎤ −2 iK⎣⎦2 Vvvt b) Depletion load MOSFET is in saturation if: vDS >−vVGS t vV>−0 t vV>−t Therefore, the current will be: 2 vDS iKvVD =−+()GS t ro 2 v iK=−+()0 V t r o Channel-Length 2 v Modulation! iKV=−()t + ro 2 v iKV=+t ro where in this case: 111 ro ===222 λKv()GS− V t λKV()0 − t λVt Jim Stiles The Univ.
    [Show full text]
  • ECE 410: VLSI Design Course Lecture Notes (Uyemura Textbook)
    ECE 410: VLSI Design Course Lecture Notes (Uyemura textbook) Professor Andrew Mason Michigan State University ECE 410, Prof. A. Mason Lecture Notes Page 2.1 CMOS Circuit Basics • CMOS = complementary MOS drain source – uses 2 types of MOSFETs gate gate to create logic functions •nMOS source drain nMOS pMOS •pMOS • CMOS Power Supply VDD CMOS – typically single power supply + CMOS VDD logic = – VDD, with Ground reference - logic circuit circuit • typically uses single power supply • VDD varies from 5V to 1V V •Logic Levels VDD logic 1 – all voltages between 0V and VDD voltages – Logic ‘1’ = VDD undefined – Logic ‘0’ = ground = 0V logic 0 voltages ECE 410, Prof. A. Mason Lecture Notes Page 2.2 Transistor Switching Characteristics •nMOS drain Vout nMOS –switching behavior gate • on = closed, when Vin > Vtn Vin nMOS – Vtn = nMOS “threshold voltage” + Vgs > Vtn = on Vgs – Vin is referenced to ground, Vin = Vgs - source • off = open, when Vin < Vtn •pMOS + source pMOS –switching behavior Vsg • on = closed, when Vin < VDD - |Vtp| - pMOS – |Vtp| = pMOS “threshold voltage” magnitude Vin Vsg > |Vtp| = on gate – Vin is referenced to ground, Vin = VDD-Vsg Vsg = VDD - Vin • off = open, when Vin > VDD - |Vtp| drain Rule to Remember: ‘source’ is at • lowest potential for nMOS • highest potential for pMOS ECE 410, Prof. A. Mason Lecture Notes Page 2.3 Transistor Digital Behavior •nMOS drain Vout nMOS Vin Vout (drain) gate Vin nMOS 1 Vs=0 device is ON + Vgs > Vtn = on 0 ? device is OFF Vgs - source •pMOS Vin Vout (drain) pMOS + source 1 ? device is OFF Vsg 0 Vs=VDD=1 device is ON - pMOS Vin Vsg > |Vtp| = on gate Vsg = VDD - Vin Vin drain pMOS Vout VDD off VDD-|Vtp| on Notice: on When Vin = low, nMOS is off, pMOS is on When Vin = high, nMOS is on, pMOS is off Vtn off Æ Only one transistor is on for each digital voltage nMOS ECE 410, Prof.
    [Show full text]
  • Monolithic Integration of Gan-Based NMOS Digital Logic Gate Circuits with E-Mode Power Gan Moshemts
    1 Proceedings of the 30th International Symposium on Power Semiconductor Devices & ICs May 13-17, 2018, Chicago, USA View metadata, citation and similar papers at core.ac.uk brought to you by CORE Monolithic Integration of GaN-Based NMOSprovided by Infoscience - ÉcoleDigital polytechnique fédérale de Lausanne Logic Gate Circuits with E-Mode Power GaN MOSHEMTs Minghua Zhu and Elison Matioli Power and Wide-band-gap Electronics Research Laboratory (POWERLAB) École Polytechnique Fédérale de Lausanne (EPFL) Lausanne, Switzerland [email protected], [email protected] Abstract— In this work, we demonstrate high-performance NOT NAND NOR NMOS GaN-based logic gates including NOT, NAND, and NOR 5 by integration of E/D-mode GaN MOSHEMTs on silicon ()WL/ 4 α = E ()WL/ substrates. The load-to-driver resistance ratio was optimized in Vout Vout Vout D (V) 3 these logic gates by using a multi-finger gate design of E-mode α =1 out α GaN MOSHEMT to increase the logic swing voltage and noise V 2 =2 α α=4 margins, and reduce the transition periods. State-of-the-art Vin VA VA VB 1 α=10 NMOS inverter was achieved with logic swing voltage of 4.93 V V at a supply voltage of 5 V, low-input noise margin of 2.13 V and B 0 (a) (c) 012345 high-input noise margin of 2.2 V at room temperature. Excellent E-mode Vin (V) high temperature performance, at 300°C, was observed with a D-mode GND Vin Vout VDD logic swing of 4.85 V, low-input noise margin of 1.85 V and high- Vin NOT output noise margin of 2.2V.
    [Show full text]
  • CMOS: Working, Construction and Applications
    CMOS: Working, Construction and Applications CMOS Working Principle and Applications The term CMOS stands for “Complementary Metal Oxide Semiconductor”. CMOS technology is one of the most popular technology in the computer chip design industry and broadly used today to form integrated circuits in numerous and varied applications. Today’s computer memories, CPUs and cell phones make use of this technology due to several key advantages. This technology makes use of both P channel and N channel semiconductor devices. One of the most popular MOSFET technologies available today is the Complementary MOS or CMOS technology. This is the dominant semiconductor technology for microprocessors, microcontroller chips, memories like RAM, ROM, EEPROM and application specific integrated circuits (ASICs). CMOS (Complementary Metal Oxide Semiconductor) The main advantage of CMOS over NMOS and BIPOLAR technology is the much smaller power dissipation. Unlike NMOS or BIPOLAR circuits, a Complementary MOS circuit has almost no static power dissipation. Power is only dissipated in case the circuit actually switches. This allows integrating more CMOS gates on an IC than in NMOS or bipolar technology, resulting in much better performance. Complementary Metal Oxide Semiconductor transistor consists of P-channel MOS (PMOS) and N- channel MOS (NMOS). Please refer the link to know more about the fabrication process of CMOS transistor. NMOS NMOS is built on a p-type substrate with n-type source and drain diffused on it. In NMOS, the majority carriers are electrons. When a high voltage is applied to the gate, the NMOS will conduct. Similarly, when a low voltage is applied to the gate, NMOS will not conduct.
    [Show full text]