01-04 - EECS 320 Semiconductor Devices Adapted from Prof J Phillips EECS 320 slides Linear Circuits In EECS 215 you had learned of linear circuits

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EECS 320 Semiconductor Devices Adapted from Prof. J. Phillips’ EECS 320 slides
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Linear Circuits In EECS 215 you had learned of linear circuits In EECS 320, you will learn of important nonlinear devices: Diodes and transistors R 2 i C R 1 v in (t) L 2i L v C + - i L C v L + -
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Diode A one way valve for current flow I V Ideal I V Actual   1 / 0 kT qV e I I Anode Cathode + - V I
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Diode Applications Rectifier Power conversion Over-voltage protection Light emitter (light emitting diode LED) Light detector (photodiode, solar cell)
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Diode Rectifiers Half-wave rectifier Full-wave rectifier
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Light Sensitive Diodes Light-emitting Diode Semiconductor Laser Visible Light Sensor
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Constant Voltage Drop Model For Diodes Simple circuit analysis using constant voltage drop model V DD = 5 V mA R V I DD D 3 . 4 000 , 1 7 . 0 5 7 . 0 You will learn why V D ~0.7V in 320! R=1k W
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Transistor tran•sis•tor (trán - zìs’ter) A solid-state electronic device that is used to control the flow of electricity in electronic equipment and consists of a small block of a semiconductor with at least three electrodes Trans(fer) + (res)istor Idea: control large output with small input This device should exhibit gain T Input Output Source
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Transistor Types Bipolar (BJT) Field-effect (FET) In general, there are two types of transistors A three terminal device in which emitter to collector current is controlled by base current A transistor in which the output current is controlled by a variable electric field (gate voltage) I B I E I C B C E Collector Base Emitter Gate Drain Source Single device Integrated circuit
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Bipolar Transistor Operation B C I I I B I E I C B C E Collector Base Emitter E C dc I I ~ “Forward Active” “Saturation” Amplifiers : typically operate in forward active mode (I C = I B ) Digital logic : typically operate in saturation (low) or off (high)
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Bipolar Transistor Equivalent Circuit I B I E I C B C E Collector Base L  I B I B v BE + - B E I C I E C v BE ~ 0.7V in forward active (you will learn why later!) B C I I For forward active operation Looks like a current amplifier with gain
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Bipolar Transistor Circuit Example When switch is closed, current can flow from the power supply to ground Current flows through 10k resistor and LED – this is the base current of the transistor Bipolar transistor turns on Current flows from power supply through 470 resistor and LED, through collector Collector current is the base current amplified by current gain b LED brightness is an indication of increased current flow for collector (gain)
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Field Effect Transistor Operation I D V DS V GS linear saturation V DS sat DS DS T GS D V V V V k I 2 Linear   2 2 T GS D V V k I Saturation k is a constant related to the device V T is the threshold voltage, where the device turns “on” Gate Drain Source No gate current, drain/source current controlled by V GS sat DS T V V V V sat T V V V V
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This note was uploaded on 07/22/2011 for the course EECS 320 taught by Professor Sun during the Fall '10 term at University of Florida.

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01-04 - EECS 320 Semiconductor Devices Adapted from Prof J Phillips EECS 320 slides Linear Circuits In EECS 215 you had learned of linear circuits

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