Exploring MOSFET Transistors & Logic Circuits: nMOS & pMOS Devices, Study notes of Logic

Download Exploring MOSFET Transistors & Logic Circuits: nMOS & pMOS Devices and more Study notes Logic in PDF only on Docsity! M. Horowitz, J. Plummer, R. Howe 1 E40M MOS Transistors, CMOS Logic Circuits, and Cheap, Powerful Computers M. Horowitz, J. Plummer, R. Howe 2 Reading • Chapter 4 in the reader • For more details look at – A&L 5.1 Digital Signals (goes in much more detail than we need) – A&L 6-6.3 MOS Devices M. Horowitz, J. Plummer, R. Howe 5 Simple Model of an nMOS Device • We will model an nMOS device by components we know – Resistor – Switch • NMOS Source = Gnd Gate = Gnd => Off Gate = Vdd => On • This really simple model is suitable for applications where there’s one value of “On” voltage. VDS iDS On Off M. Horowitz, J. Plummer, R. Howe 6 How Does an nMOS Transistor Actually Work? (FYI – not essential for this course) http://www.extremetech.com/wp- content/uploads/2014/09/close+finfet.jpg M. Horowitz, J. Plummer, R. Howe 7 Problem With nMOS Device • While an nMOS device makes a great switch to Gnd • It doesn’t work that well if we want to connect to Vdd – To turn transistor on • Gate needs to be higher than source – But we want the source to be at Vdd • Oops … M. Horowitz, J. Plummer, R. Howe 10 How Does a pMOS Transistor Actually Work? (FYI – not part of this course) M. Horowitz, J. Plummer, R. Howe 11 nMOS and pMOS Devices “Complement” Each Other – Complementary MOS or CMOS • PMOS Source = Vdd (+ supply) Gate = Gnd => On Gate = Vdd => Off • NMOS Source = Gnd Gate = Gnd => Off Gate = Vdd => On Ron M. Horowitz, J. Plummer, R. Howe 12 MOS Transistor Summary • MOS transistors are extremely useful devices – Almost all of your electronics uses them on the inside – Including your phone, laptop, WiFi and Bluetooth, and your Arduino • Come in two “flavors” – nMOS • It is a switch which connects source to drain • If the gate-to-source voltage is greater than Vth (around 1 V) – Positive gate-to-source voltages turn the device on. – pMOS • It is a switch which connects source to drain • If the gate-to-source voltage is less than Vth (around -1 V) – Negative gate-to-source voltages turn the device on … and there’s zero current into the gate! M. Horowitz, J. Plummer, R. Howe 15 What Does This Circuit Do? • Now consider Vin = VDD In Out VDD pMOS nMOS M. Horowitz, J. Plummer, R. Howe 16 Building Logic Gates from MOS Transistors • Remember Boolean Logic? – AND, OR – NAND = Not-AND = AND followed by Inverter • Output is only low when A and B are true (high) – NOR = Not-OR = OR followed by Inverter • Output is low when either A or B is true (high) • You can make them from MOS devices – But only the inverting gates (NOR and NAND) M. Horowitz, J. Plummer, R. Howe 17 Building a CMOS NAND Gate • Output should be low if both input are high (true) • Output should be high if either input is low (false) M. Horowitz, J. Plummer, R. Howe 20 HOW THE MOS TRANSISTOR CHANGED THE WORLD … M. Horowitz, J. Plummer, R. Howe 21 First Computing Machines Were Mechanical Picture of a version of the Babbage difference engine built by the Museum of Science, UK “The calculating section of Difference Engine No. 2, has 4,000 moving parts (excluding the printing mechanism) and weighs 2.6 tons. It is seven feet high, eleven feet long and eighteen inches in depth” M. Horowitz, J. Plummer, R. Howe 22 Moving Electrons is Easier than Moving Metal • Building electronics: – Started with tubes, then miniature tubes – Transistors, then miniature transistors – Components were getting cheaper, more reliable but: • There is a minimum cost of a component (storage, handling …) • Total system cost was proportional to complexity • Integrated circuits changed that – Printed a circuit, like you print a picture, • Create components in parallel • Cost no longer depended on # of devices M. Horowitz, J. Plummer, R. Howe 25 1 I nt r oduc t i on - Chapt er 1 SI LI CON VLSI TECHNOLOGY Fundament al s , Pr ac t i c e and Model i ng By Pl ummer , Deal & Gr i f f i n © 2000 by Pr ent i c e Hal l Upper Saddl e Ri ver NJ I NTRODUCTI ON - Chapt er 1 i n t he Text • Thi s c our s e i s bas i c al l y about s i l i c on c hi p f abr i c at i on, t he t ec hnol ogi es us ed t o manuf ac t ur e I Cs . • We wi l l pl ac e a s pec i al emphas i s on c omput er s i mul at i on t ool s t o hel p under s t and t hes e pr oc es s es and as des i gn t ool s . • Thes e s i mul at i on t ool s ar e mor e s ophi s t i c at ed i n s ome t ec hnol ogy ar eas t han i n ot her s , but i n al l ar eas t hey have made t r emendous pr ogr es s i n r ec ent year s . • 1960 and 1990 i nt egr at ed c i r c ui t s . • Pr ogr es s due t o: Feat ur e s i ze r educ t i on - 0. 7X/ 3 year s ( Moor e’ s Law) . I nc r eas i ng c hi p s i ze - ? 16% per year . “Cr eat i vi t y” i n i mpl ement i ng f unc t i ons . Point Contact Transistor First Integrated Circuit Modern Microprocessor 1 I nt r oduc t i on - Chapt er 1 SI LI CON VLSI TECHNOLOGY Fundament al s , Pr ac t i c e and Model i ng By Pl u mer , Deal & Gr i f f i n © 2000 by Pr ent i c e Hal l Upper Saddl e Ri ver NJ I NTRODUCTI ON - Chapt er 1 i n t he Text • Thi s c our s e i s bas i c al l y about s i l i c on c hi p f abr i c at i on, t he t ec hnol ogi es us ed t o manuf ac t ur e I Cs . • We wi l l pl ac e a s pec i al emphas i s on c omput er s i mul at i on t ool s t o hel p under s t and t hes e pr oc es s es and as des i gn t ool s . • Thes e s i mul at i on t ool s ar e mor e s ophi s t i c at ed i n s ome t ec hnol ogy ar eas t han i n ot her s , but i n al l ar eas t hey have made t r emendous pr ogr es s i n r ec ent year s . • 1960 and 1990 i nt egr at ed c i r c ui t s . • Pr ogr es s due t o: Feat ur e s i ze r educ t i on - 0. 7X/ 3 year s ( oor e’ s La ) . I nc r eas i ng c hi p s i ze - ? 16% per year . “Cr eat i vi t y” i n i mpl ement i ng f unc t i ons . From This To This To This Miniaturization Progress Over 50 Years • Modern silicon chips have > 109 components in 1 cm2 area. M. Horowitz, J. Plummer, R. Howe 26 1965 - Moore Intel Microprocessors Moore’s “Law” • “The complexity for minimum component costs has increased at a rate of roughly a factor of 2 per year.” Gordon Moore, 1965 M. Horowitz, J. Plummer, R. Howe 27 Transistors per mm2 Kaizad Mistry, Intel Technology and Manufacturing Day, March 28, 2017