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Chapter 11

CMOS and TTL Circuits

By Taweesak Reungpeerakul

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Contents

Basic Operational Characteristics and Parameters

CMOS Circuits TTL Circuits

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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 Immunity

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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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Loading and Fan-out

Fan-out

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CMOS Loading

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TTL Loading

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11.2 CMOS Circuits MOSFET

n-channel p-channel

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CMOS Inverter

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CMOS NAND Gate

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CMOS NOR Gate

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Open-drain Gate

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Tristate CMOS Gate

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11.3 TTL Circuits

The Bipolar Junction Transistor (BJT)

TTL Inverter TTL NAND Gate Open-collector Gates Tristate TTL Gates

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The Bipolar Junction Transistor (BJT)

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TTL Inverter

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TTL NAND Gate

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Open-collector Gates

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Tristate TTL Gate