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Digital Electronics 2 - Transistors Introduction to CAD Naehyuck Chang naehyuck@snu.ac.kr
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SNU naehyuck@snu.ac.kr Transistor (1) PNP and NPN Transistors Silicon transistors Germanium transistors Theory of operation
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SNU naehyuck@snu.ac.kr Transistor (2) Types of transistor Low/high frequency Low/high power Field effect transistor
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SNU naehyuck@snu.ac.kr Transistor (3) Parallel connection current hogging Darlington transistor
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SNU naehyuck@snu.ac.kr Transistor (4) Transistor switch Base resistor Collector resistor
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SNU naehyuck@snu.ac.kr Transistor (5) Characteristics of a simple inverter
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SNU naehyuck@snu.ac.kr Transistor (6) Diode switches versus transistor switches
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Logic gates Introduction to CAD Naehyuck Chang naehyuck@snu.ac.kr
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SNU naehyuck@snu.ac.kr Ideal inverter Basic primitive gate Rail-to-rail swing 1/2 VDD threshold Zero output impedance Infinite slew rate Zero propagate delay Characteristics Propagation delay TPD Rise time TR Fall time TF Output characteristics VOH, VOL, ROH and ROL
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SNU naehyuck@snu.ac.kr RTL Fast 1 to 0 transition Slow 0 to 1 transition Low ROL High ROH Fan-out sensitive VOH Quiescent power consumption when output is 0.
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SNU naehyuck@snu.ac.kr DTL Less fan-out sensitive VOH Improved threshold Worse 0 to 1 transition delay Improved quiescent power consumption
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SNU naehyuck@snu.ac.kr Emitter common switch Saturation Fast turn on Slow turn off
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SNU naehyuck@snu.ac.kr TTL Input is high
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SNU naehyuck@snu.ac.kr TTL (contd.) Speed up turn-off switching
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SNU naehyuck@snu.ac.kr TTL (contd.) Evolution from RTL Fast 1 to 0 transition? Slow 0 to 1 transition? Low ROL? High ROH? Fan-out sensitive VOH? Quiescent power consumption when output is 0?
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SNU naehyuck@snu.ac.kr TTL (contd.) Fast 0 to 1 switching Low ROH
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SNU naehyuck@snu.ac.kr TTL (contd.) Totem Pole Pulling up and down
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SNU naehyuck@snu.ac.kr TTL (contd.) Driver stage Output stage Resistor Diode
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SNU naehyuck@snu.ac.kr TTL (contd.) Vin = High
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SNU naehyuck@snu.ac.kr TTL (contd.) Vin = Low
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SNU naehyuck@snu.ac.kr TTL (contd.) Threshold voltage Input current when logic is high/when logic is low Quiescent power consumption when logic is high/when logic is low Totem pole output stage Diode and resistor VOH/VOL, ROH/ROL
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SNU naehyuck@snu.ac.kr Note: Some figures are from Microelectronic Circuits fourth edition by Sedra and Smith, Oxford.
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