Lecture 8Transistors and CMOS

Lecture 8Transistors and CMOS

TopicsTopics Combinational Circuits Quiz Structural VHDL Lab 2 VHDL: Decoders, Multiplexers Demultiplexers

Readings 3.Readings 3.

September 25, 2003

CSCE 211 Digital Design

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OverviewOverview

Last TimeLast Time Lab 3 – VHDL Lab 3 Deliverables:

NewNew Encoders/Priority Encoders Transistors CMOS gates Review for test

HistoryHistory Invention of transistor

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Honors College: Advisement Honors College: Advisement

Appointment Sign-up begins Appointment Sign-up begins Wednesday October 1 8:00AM Outside main office 2nd floor Harper

Advisement begins Monday October 6Advisement begins Monday October 6

CSCE Classes (lower level)CSCE Classes (lower level) CSCE 145 MW 2:30-3:45 Fuchs CSCE 146 TTH 9:30-10:45 Bowles CSCE 212H TTH 12:30-1:45 Matthews CSCE 240 MWF 9:05-9:55 Fuchs CSCE 245 MW 4:00-5:15

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Lab 3 DeliverablesLab 3 Deliverables

1.1. VHDL for 74LS47’ where the ’ means don’t care for VHDL for 74LS47’ where the ’ means don’t care for 10 … 15 using functions given in class (slide )10 … 15 using functions given in class (slide )

2.2. Schematic using components (symbols) made for Schematic using components (symbols) made for 74LS47 and 74LS153 (Mux). Add output ports to 74LS47 and 74LS153 (Mux). Add output ports to outputs of 74LS47 and label them with the pin outputs of 74LS47 and label them with the pin numbers for your seven segment display digit. The numbers for your seven segment display digit. The input ports should also be labeled. input ports should also be labeled.

3.3. Circuit for selecting one base-4 number with a mux Circuit for selecting one base-4 number with a mux and displaying it on the even segment display.and displaying it on the even segment display. You must use the DIP switch to set the input of four base-4

numbers. The select line inputs will be just wires.

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Hot BatteriesHot Batteries

You should regularly check your batteries “slightly You should regularly check your batteries “slightly warm” is OK but hot indicates that your circuit has a warm” is OK but hot indicates that your circuit has a short circuit.short circuit.

Unplug quickly and check.Unplug quickly and check.1. Look for direct lines Vcc to GND.

2. Remember you need 330 ohm resistors in series with LEDs and that includes segments of the seven segment display.

3. Recheck sections of the breadboard.

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Functions for 74LS47 with don’t caresFunctions for 74LS47 with don’t caresa(D,C,B,A) = D + Aa(D,C,B,A) = D + A..C + AC + A..B + A’B + A’..C’ C’

b(D,C,B,A) = D + (D'*C') + (A'*B') + (A*B) (aj)b(D,C,B,A) = D + (D'*C') + (A'*B') + (A*B) (aj)

c <= a or not b or d c <= a or not b or d (david)(david)

d = d =

e = A(bar) and (B or C(bar)) e = A(bar) and (B or C(bar)) (jeremy/patrick) (jeremy/patrick)

f = D + A'B' + B'C + A'BC f = D + A'B' + B'C + A'BC (jon)(jon)

g=D + B'C + C'B + A'B g=D + B'C + C'B + A'B (msbell)(msbell)

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Karnaugh Map SimplificationKarnaugh Map SimplificationOn a real 74LS47 the outputs for 10, …15 are not don’t cares.On a real 74LS47 the outputs for 10, …15 are not don’t cares.

They would indicate errors in BCD input. We could use the period for that. They would indicate errors in BCD input. We could use the period for that.

period(D,C,B,A)=SUM( )period(D,C,B,A)=SUM( )

dc(D,C,B,A) = SUM( )dc(D,C,B,A) = SUM( )

BADC 00 01 11 10

00

01

11

10

A

D

C

B

period(D,C,B,A) =period(D,C,B,A) =

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TransistorsTransistors

HistoryHistory

1790s Ben Franklin “assigns” negative charge to 1790s Ben Franklin “assigns” negative charge to electronselectrons

1898 Thompson discovers the electron1898 Thompson discovers the electron

1947 Shockley, Bardeen and Brattain “invent” 1947 Shockley, Bardeen and Brattain “invent” transistortransistor

1958 first Integrated Circuit, Texas Instruments1958 first Integrated Circuit, Texas Instruments

1971 Intel 4004, microprocessor, Ted Hoff1971 Intel 4004, microprocessor, Ted Hoff

TimelineTimeline

http://www.pbs.org/transistor/http://www.pbs.org/transistor/

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Transistor: Water Flow ModelTransistor: Water Flow ModelWater flow in B raises the plunger so that water can flow from C to E.

Small flow turns on and off bigger flow.

Put signal on B, transfer signal C to E

Reference: http://www.satcure-focus.com/tutor/page4.htm

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Transistor TerminologyTransistor Terminology

Conductor – electrons easily passed from one atom to Conductor – electrons easily passed from one atom to next (copper every atom has loose electron)next (copper every atom has loose electron)

Insulator – electrons tightly tied down to atoms, no flowInsulator – electrons tightly tied down to atoms, no flow

Semiconductor – by adding impurities (doping) can be Semiconductor – by adding impurities (doping) can be changed to increase conductivitychanged to increase conductivity

Silicon wafer – used for IC circuitsSilicon wafer – used for IC circuits

N-type - silicon doped with boron (excess electrons)N-type - silicon doped with boron (excess electrons)

P-ype - silicon doped with phosphorous (excess P-ype - silicon doped with phosphorous (excess “holes” lack of electrons)“holes” lack of electrons)

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TransistorTransistor

Reference: http://www.intel.com/education/transworks/

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TransistorTransistor

Reference: http://www.intel.com/education/transworks/

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TransistorTransistor

Reference: http://www.intel.com/education/transworks/

Put Positive charge on gate.

This attracts electrons into gap.

This allows electrons to pass freely through the gap.

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TransistorTransistor

Reference: http://www.intel.com/education/transworks/

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TransistorTransistor

Reference: http://www.intel.com/education/transworks/

Take positive charge offGate

This stops attractingelectrons.

This shuts off the flow.

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N channel transitorN channel transitor

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P channel TransistorP channel Transistor

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CMOS InverterCMOS Inverter

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CMOS NANDCMOS NAND

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What’s This?What’s This?

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Test / Sample TestTest / Sample Test