241-208 CH11 1 Chapter 11 CMOS and TTL Circuits By Taweesak Reungpeerakul
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11.1 Basic Operational Characteristics and Parameters
DC Supply Voltage CMOS: +5 or +3.3 Volts TTL : +5 Volts
CMOS Logic Levels +5 V Supply
VIH : 3.5-5 V VOH : 4.4-5 V
VIL : 0-1.5 V VOL : 0-0.33 V +3.3 V Supply
VIH : 2-3.3 V VOH : 2.4-3.3 V
VIL : 0-0.8 V VOL : 0-0.4 V TTL Logic Levels (+5 V Supply)
VIH : 2-5 V VOH : 2.4-5 V
VIL : 0-0.8 V VOL : 0-0.4 V
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11.1 Basic Operational Characteristics and Parameters (cont.)
Noise Immunity Noise Margin Power Dissipation Propagation Delay (tPHL & tPLH) Speed-Power Product Loading and Fan-out
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Noise Margin VNH = VOH(min) – VIH(min) VNL = VIL(max) – VOL(max) Find VNH & VNL for 5 V CMOS
VNH = VOH(min) – VIH(min)
= 4.4 – 3.5
= 0.9 V VNL = VIL(max) – VOL(max)
= 1.5 – 0.33
= 1.17 V
Question: Find VNH & VNL for 5 V TTL
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Power Dissipation ICC = ICCH+ICCL
2 PD = VCC*ICC
Example: find PD
2 µA when HI 3.6 µA when LO 50% Duty cycle
Power VS Frequency
ICC= 2.8 µAPD = (5V)(2.8µA) = 14 µW
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11.3 TTL Circuits
The Bipolar Junction Transistor (BJT)
TTL Inverter TTL NAND Gate Open-collector Gates Tristate TTL Gates