"Lessons in Electric Circuits, Volume III -- Semiconductors"
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Unit-1 Mphycc-7 Ujt
UNIT-1 MPHYCC-7 UJT The Unijunction Transistor or UJT for short, is another solid state three terminal device that can be used in gate pulse, timing circuits and trigger generator applications to switch and control either thyristors and triac’s for AC power control type applications. Like diodes, unijunction transistors are constructed from separate P-type and N-type semiconductor materials forming a single (hence its name Uni-Junction) PN-junction within the main conducting N-type channel of the device. Although the Unijunction Transistor has the name of a transistor, its switching characteristics are very different from those of a conventional bipolar or field effect transistor as it can not be used to amplify a signal but instead is used as a ON-OFF switching transistor. UJT’s have unidirectional conductivity and negative impedance characteristics acting more like a variable voltage divider during breakdown. Like N-channel FET’s, the UJT consists of a single solid piece of N-type semiconductor material forming the main current carrying channel with its two outer connections marked as Base 2 ( B2 ) and Base 1 ( B1 ). The third connection, confusingly marked as the Emitter ( E ) is located along the channel. The emitter terminal is represented by an arrow pointing from the P-type emitter to the N-type base. The Emitter rectifying p-n junction of the unijunction transistor is formed by fusing the P-type material into the N-type silicon channel. However, P-channel UJT’s with an N- type Emitter terminal are also available but these are little used. -
Special Diodes 2113
CHAPTER54 Learning Objectives ➣ Zener Diode SPECIAL ➣ Voltage Regulation ➣ Zener Diode as Peak Clipper DIODES ➣ Meter Protection ➣ Zener Diode as a Reference Element ➣ Tunneling Effect ➣ Tunnel Diode ➣ Tunnel Diode Oscillator ➣ Varactor Diode ➣ PIN Diode ➣ Schottky Diode ➣ Step Recovery Diode ➣ Gunn Diode ➣ IMPATT Diode Ç A major application for zener diodes is voltage regulation in dc power supplies. Zener diode maintains a nearly constant dc voltage under the proper operating conditions. 2112 Electrical Technology 54.1. Zener Diode It is a reverse-biased heavily-doped silicon (or germanium) P-N junction diode which is oper- ated in the breakdown region where current is limited by both external resistance and power dissipa- tion of the diode. Silicon is perferred to Ge because of its higher temperature and current capability. As seen from Art. 52.3, when a diode breaks down, both Zener and avalanche effects are present although usually one or the other predominates depending on the value of reverse voltage. At reverse voltages less than 6 V, Zener effect predominates whereas above 6 V, avalanche effect is predomi- nant. Strictly speaking, the first one should be called Zener diode and the second one as avalanche diode but the general practice is to call both types as Zener diodes. Zener breakdown occurs due to breaking of covalent bonds by the strong electric field set up in the depletion region by the reverse voltage. It produces an extremely large number of electrons and holes which constitute the reverse saturation current (now called Zener current, Iz) whose value is limited only by the external resistance in the circuit. -
Lecture17 08 04 2010
EE40 Lecture 17 Josh Hug 8/04/2010 EE40 Summer 2010 Hug 1 Logistics • HW8 will be due Friday • Mini-midterm 3 next Wednesday – 80/160 points will be a take-home set of design problems which will utilize techniques we’ve covered in class • Handed out Friday • Due next Wednesday – Other 80/160 will be an in class midterm covering HW7 and HW8 • Final will include Friday and Monday lecture, Midterm won’t – Design problems will provide practice EE40 Summer 2010 Hug 2 Project 2 • Booster lab actually due next week – For Booster lab, ignore circuit simulation, though it may be instructive to try the Falstad simulator • Project 2 due next Wednesday – Presentation details to come [won’t be mandatory, but we will ask everyone about their circuits at some point] EE40 Summer 2010 Hug 3 Project 2 • For those of you who want to demo Project 2, we’ll be doing demos in lab on Wednesday at some point – Will schedule via online survey EE40 Summer 2010 Hug 4 CMOS/NMOS Design Correction • (Sent by email) • My on-the-fly explanation was correct, but not the most efficient way – If your FET circuit is implementing a logic function with a bar over it, i.e. • 푍 = 퐴 + 퐵퐶 + 퐷 + 퐸퐹 퐺 + 퐻 – Then don’t put an inverter at the output, it just makes things harder and less efficient • Sorry, on-the-fly-explanations can be dicey EE40 Summer 2010 Hug 5 CMOS • CMOS Summary: – No need for a pull-up or pull-down resistor • Though you can avoid this even with purely NMOS logic (see HW7) – Greatly reduced static power dissipation vs. -
TRIAC Overvoltage Protection Using a Transil™
AN1966 Application note TRIAC overvoltage protection using a Transil™ Introduction In most of their applications, TRIACs are directly exposed to overvoltages coming from the mains, as described in IEC 61000-4-5 or IEC 61000-4-4 standards. When TRIACs are used to drive resistive loads (ex: temperature regulation), it is essential to provide them with efficient overvoltage protection to prevent any turn-on in breakover mode that could lead to device damage. A traditional method to clamp the voltage is to use a varistor in parallel across the TRIAC. But with high power loads (a few kW), the current through the varistor is very high in case of surge voltages (a few hundred amperes). The varistor is then not efficient enough, due to its dynamic resistor, to limit the TRIAC voltage to a low value. We present here a solution that can be used for these kinds of applications and also for all applications where TRIAC voltage protection is required. It should be noted that the overvoltages could also come from the overvoltages that appear at device turn-off due to the TRIAC holding current. This phenomenon occurs mainly with TRIACs controlling low rms current (15-50 mA), high inductive loads like valves. For more information about such behavior, please refer to AN1172. Contents 1 Why overvoltage protection is required . 2 2 Overvoltage protection solution . 3 3 Transil choice for efficient TRIAC voltage protection . 6 3.1 Normal operation: check VRM voltage . 6 3.2 Surge voltage clamping: check max VCL voltage . 6 4 Experimental validation example . 8 5 Conclusion . -
Thyristors.Pdf
THYRISTORS Electronic Devices, 9th edition © 2012 Pearson Education. Upper Saddle River, NJ, 07458. Thomas L. Floyd All rights reserved. Thyristors Thyristors are a class of semiconductor devices characterized by 4-layers of alternating p and n material. Four-layer devices act as either open or closed switches; for this reason, they are most frequently used in control applications. Some thyristors and their symbols are (a) 4-layer diode (b) SCR (c) Diac (d) Triac (e) SCS Electronic Devices, 9th edition © 2012 Pearson Education. Upper Saddle River, NJ, 07458. Thomas L. Floyd All rights reserved. The Four-Layer Diode The 4-layer diode (or Shockley diode) is a type of thyristor that acts something like an ordinary diode but conducts in the forward direction only after a certain anode to cathode voltage called the forward-breakover voltage is reached. The basic construction of a 4-layer diode and its schematic symbol are shown The 4-layer diode has two leads, labeled the anode (A) and the Anode (A) A cathode (K). p 1 n The symbol reminds you that it acts 2 p like a diode. It does not conduct 3 when it is reverse-biased. n Cathode (K) K Electronic Devices, 9th edition © 2012 Pearson Education. Upper Saddle River, NJ, 07458. Thomas L. Floyd All rights reserved. The Four-Layer Diode The concept of 4-layer devices is usually shown as an equivalent circuit of a pnp and an npn transistor. Ideally, these devices would not conduct, but when forward biased, if there is sufficient leakage current in the upper pnp device, it can act as base current to the lower npn device causing it to conduct and bringing both transistors into saturation. -
A Vertical Resonant Tunneling Transistor for Application in Digital Logic Circuits
1028 IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 48, NO. 6, JUNE 2001 A Vertical Resonant Tunneling Transistor for Application in Digital Logic Circuits Jürgen Stock, Jörg Malindretos, Klaus Michael Indlekofer, Michael Pöttgens, Arno Förster, and Hans Lüth Abstract—A vertical resonant tunneling transistor (VRTT) has In this paper, we report on the fabrication of a vertical res- been developed, its properties and its application in digital logic onant tunneling transistor (VRTT) with low peak voltage and circuits based on the monostable-bistable transition logic element good peak current control by means of a Schottky gate. The (MOBILE) principle are described. The device consists of a small mesa resonant tunneling diode (RTD) in the GaAs/AlAs material asymmetric behavior of the current-voltage ( ) character- system surrounded by a Schottky gate. We obtain low peak voltages istics is analyzed and the transistors are characterized with re- using InGaAs in the quantum well and the devices show an excel- spect to their peak voltage, peak-to-valley ratio (PVR), peak cur- lent peak current control by means of an applied gate voltage. A rent density, and gate function. We demonstrate the switching self latching inverter circuit has been fabricated using two VRTTs functionality of a self latching inverter circuit consisting of two and the switching functionality was demonstrated at low frequen- cies. VRTTs. Index Terms—Monostable-bistable transition logic element (MOBILE), monostable-to-bistable transition, resonant tunneling II. DEVICE FABRICATION diode (RTD), resonant tunneling transistor. A. Layer Structure The epitaxial structure used to fabricate the VRTT device was I. INTRODUCTION grown by molecular beam epitaxy (MBE) on semi-insulating N recent years, several new memory and logic circuits based (100)-orientated GaAs substrate. -
An Integrated Semiconductor Device Enabling Non-Optical Genome Sequencing
ARTICLE doi:10.1038/nature10242 An integrated semiconductor device enabling non-optical genome sequencing Jonathan M. Rothberg1, Wolfgang Hinz1, Todd M. Rearick1, Jonathan Schultz1, William Mileski1, Mel Davey1, John H. Leamon1, Kim Johnson1, Mark J. Milgrew1, Matthew Edwards1, Jeremy Hoon1, Jan F. Simons1, David Marran1, Jason W. Myers1, John F. Davidson1, Annika Branting1, John R. Nobile1, Bernard P. Puc1, David Light1, Travis A. Clark1, Martin Huber1, Jeffrey T. Branciforte1, Isaac B. Stoner1, Simon E. Cawley1, Michael Lyons1, Yutao Fu1, Nils Homer1, Marina Sedova1, Xin Miao1, Brian Reed1, Jeffrey Sabina1, Erika Feierstein1, Michelle Schorn1, Mohammad Alanjary1, Eileen Dimalanta1, Devin Dressman1, Rachel Kasinskas1, Tanya Sokolsky1, Jacqueline A. Fidanza1, Eugeni Namsaraev1, Kevin J. McKernan1, Alan Williams1, G. Thomas Roth1 & James Bustillo1 The seminal importance of DNA sequencing to the life sciences, biotechnology and medicine has driven the search for more scalable and lower-cost solutions. Here we describe a DNA sequencing technology in which scalable, low-cost semiconductor manufacturing techniques are used to make an integrated circuit able to directly perform non-optical DNA sequencing of genomes. Sequence data are obtained by directly sensing the ions produced by template-directed DNA polymerase synthesis using all-natural nucleotides on this massively parallel semiconductor-sensing device or ion chip. The ion chip contains ion-sensitive, field-effect transistor-based sensors in perfect register with 1.2 million wells, which provide confinement and allow parallel, simultaneous detection of independent sequencing reactions. Use of the most widely used technology for constructing integrated circuits, the complementary metal-oxide semiconductor (CMOS) process, allows for low-cost, large-scale production and scaling of the device to higher densities and larger array sizes. -
Triac Control with a Microcontroller Powered from a Positive Supply
AN440 Application note Triac control with a microcontroller powered from a positive supply Introduction This application note explains how to implement a control circuit to drive an AC switch (Triac, ACS or ACST) in case the microcontroller unit (MCU) is supplied with a positive voltage. The driving circuit will also depends on the kind of Triac used and also if other supplies (positive or negative) are available. We also deal about the case of insulated or non-insulated supplies. It is recommended to refer to AN4564 which explains why positive supplies are usually implemented and how simple solutions can be implemented to get a negative supply. Refer also to AN3168 for information about AC switch control circuits in case the microcontroller is supplied with a negative power supply. AN440 - Rev 4 - March 2020 www.st.com For further information contact your local STMicroelectronics sales office. AN440 Positive supply defintion and AC switch triggering quadrants 1 Positive supply defintion and AC switch triggering quadrants 1.1 Positive power supply A positive power supply is a supply where its reference level (VSS) is connected to the mains (line or neutral). The VDD level is then above the mains terminal as shown in Figure 1. If the supply is a 5 V power supply, then VDD is 5 V above the mains reference. This is why such a supply is called a positive supply (compared to a negative supply as shown in AN3168). Figure 1. Positive supply basic schematic 1.2 AC switch triggering quadrants To switch-on an AC switch, like any bipolar device, a gate current must be applied between its gate pin (G) and its drive reference terminal (refer also to AN3168). -
Diode Logic). • Explain the Need for Introducing Transistors in the Output (DTL and TTL
Lecture 02: Logic Families R.J. Harris & D.G. Bailey Objectives • Show how diodes can be used to form logic gates (Diode logic). • Explain the need for introducing transistors in the output (DTL and TTL). • Explain why Schottky transistors improve the speed of gates. • Describe the operating principles of CMOS logic gates. • Explain the definitions of noise margin, fanout, propagation delay, rise and fall time. Semester 2 - 2006 Digital Electronics Slide 2 Review of Previous Lecture • You can now: – Describe the important differences between analogue and digital signals. – Show how to represent more than two levels using digital signals. – Manipulate different codes for representing numbers and letters: • natural binary, signed binary, twos complement, offset binary, Gray codes, ASCII characters. – Show how to convert between binary and base 10. – Write down the logic symbols for • AND, OR, NOT, NAND and NOR gates. – Draw up a truth table to represent relationships between inputs and outputs of a logic circuit. Semester 2 - 2006 Digital Electronics Slide 3 Presentation Outline • Diode Transistor Logic • TTL • Schottky TTL • CMOS • Tristate logic outputs • Definitions: – Noise margin, fanout – Timing: rise and fall times, propagation delay – Power dissipation • Power supply decoupling Semester 2 - 2006 Digital Electronics Slide 4 Diode Logic – AND Gate • Recall that a diode behaves like a switch. – When the diode is forward biased, the switch is closed, allowing a current to flow through it. When reverse biased, it is like a switch that is turned off - no current flows. • First we shall look at an AND gate. – If either input A or input B goes low, it will forward bias the corresponding diode. -
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. -
Michael J. Chudobiak Ii
New Approaches For Designing High Voltage, High Current Silicon Step Recovery Diodes for Pulse Sharpening Applications by Michael John Chudobiak, B.Sc. (Hons.) A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy Ottawa-Carleton Institute for Electrical Engineering Department of Electronics Carleton University Ottawa, Ontario, Canada July 30, 1996 Copyright 1996, Michael J. Chudobiak ii Acceptance Sheet iii Abstract Two promising new approaches for designing step recovery diodes (SRDs) for operation at voltages of several hundred volts are considered in this thesis. An entirely new type of step recovery diode is presented, which can operate with reverse voltages of several hundred volts and which exhibits exceptionally long lifetimes of several microseconds. These diodes have been named “wide field step recovery diodes (WFSRDs)”. Experimental results for two batches of fabricated devices are presented for 300 V operation into a 50 Ω load. Pulse sharpening operation with rise times as low as 0.9 ns and storage times as large as 9 ns has been observed for fabricated diodes with effective carrier lifetimes of 4500 ns. Pulse sharpening operation has also been observed with rise times as low as 0.6 ns and storage times as large as 30 ns for fabricated diodes with effective carrier lifetimes of 950 ns. These diodes have a diffused p-π-n structure. A comprehensive design theory is developed by considering the nature of the reverse transient in the diode. A method of calculating the breakdown voltage of diffused structures without resorting to simulations is also presented. -
Digital Logic and Design (Course Code: EE222) Ltlecture 6: Lliogic Famili Es
Indian Institute of Technology Jodhpur, Year 2018‐2019 Digital Logic and Design (Course Code: EE222) LtLecture 6: LiLogic Fam ilies Course Instructor: Shree Prakash Tiwari EilEmail: sptiwari@iitj .ac.i n Webpage: http://home.iitj.ac.in/~sptiwari/ Course related documents will be uploaded on http://home.iitj.ac.in/~sptiwari/DLD/ Note: The information provided in the slides are taken form text books Digital Electronics (including Mano & Ciletti), and various other resources from internet, for teaching/academic use only 1 Overview •Early families (DL, RTL) • TTL •Evolution of TTL family • CMOS family and its evolution 2 Logic families Diode Logic (DL) •simpp;lest; does not scale •NOT not possible (need = an active element) Resistor-Transistor Logic (RTL) • replace diode switch with a tittransistor switc h •can be cascaded = • large power draw 3 Logic families Diode-Transistor Logic (DTL) • essentially diode logic with transistor amplification • reduced power consumption •faster than RTL = DL AND gate Saturating inverter 4 Logic Families • The bipolar transistor as a logical switch TTL Bipolar Transistor-Transistor Logic (TTL) •First introduced by in 1964 (Texas Instruments) •TTL has shaped digital technology in many ways • Standard TTL family (e.g. 7400) is obsolete •Newer TTL families used (e.g. 74ALS00) 6 TTL Bipolar Transistor-Transistor Logic (TTL) Distinct features •Multi‐emitter transistors 7 TTL A Standard TTL NAND gate 8 TTL A standard TTL NAND gate with open collector output 9 TTL evolution Schottky series (74LS00) TTL •A major