UNIT – V CMOS LOGIC: CMOS logic levels, MOS transistors, Basic CMOS Inverter, NAND and NOR gates, CMOS AND-OR-INVERT and OR-AND-INVERT gates, Implementation of any function using CMOS logic. COMBINATIONAL CIRCUITS USING TTL 74XX ICS Study of logic gates using 74XX ICs, Four-bit parallel adder(IC 7483),Comparator(IC 7485), Decoder(IC 74138, IC 74154), BCD-to-7-segment decoder(IC 7447), Encoder(IC 74147), Multiplexer(IC74151), Demultiplexer (IC 74154). SEQUNTIAL CIRCUITS USING TTL 74XX ICS Flip Flops (IC 7474, IC 7473), Shift Registers, Universal Shift Register(IC 74194), 4- bit asynchronous binary counter(IC 7493).

CMOS LOGIC CMOS logic levels MOS transistors Basic CMOS Inverter NAND and NOR gates CMOS AND-OR-INVERT OR-AND-INVERT gates Implementation of any function using CMOS logic

INTEGRATED CIRCUIT TECHNOLOGIES FOR DIGITAL ICs BIPOLAR TECHNOLOGY- SSI AND MSI TTL (WIDELY USED) ECL UNIPOLAR TECHNOLOGY(MOSFET) - LSI, VLSI AND ULSI CMOS NMOS

TTL AND CMOS SERIES TTL SERIES CMOS SERIES(5V and 3.3V) 74 – Standard TTL (no letter) 74S- Schottky TTL 74AS – Advanc Schottky TTL 74LS – Low power Schottky TTL 74ALS-Advanced Low power Schottky TTL 74F-Fast TTL HC – HIGH SPEED CMOS AHC- ADVANCED HIGH SPPED CMOS LV – LOW VOLATGE CMOS HCT – HIGH SPEED CMOS AND TTL COMPATIBLE

MOS OVER TTL INEXPENSIVE AND EASY TO FABRICATE OCCUPIES LESS SPACE CONSUMES LITTLE POWER RESISTORS CAN BE CONSTRUCTED WITH MOSFETS ACCOMODATES MORE NO. OF ELEMENTS THAN TTL IN SAME SPACE SUITABLE FOR COMPLEX ICs

MOS TRANSISTORS DEPLETION MOSFET ENHANCEMENT MOSFET PMOS- NMOS- ON(GATE VOLTAGE = LOGIC 0) OFF(GATE VOLTAGE = LOGIC 1) AND OPERATION IN A PARALLEL CONNECTIVITY OR OPERATION IN A SERIES CONNECTIVITY NMOS- ON(GATE VOLTAGE = LOGIC 1) OFF(GATE VOLTAGE = LOGIC 0) AND OPERATION IN A SERIES CONNECTIVITY OR OPERATION IN A PARALLEL CONNECTIVITY BASICALLY USED AS A SWITCH

MOS TRANSISTORS NMOS PMOS CMOS

NMOS OVER PMOS PACKAGE DENSITY IS MORE ABOUT THREE TIMES FASTER MOSTLY MEMORIES, PROCESSORS AND PERIPHERAL DEVICES ARE AVALIABLE IN NMOS PMOS AND NMOS ARE ECONOMICAL THAN CMOS

SYMBOL AND SWITCHING OF MOSFETs

NMOS AS RESISTOR, NAND AND NOR

NMOS CHARACTERISTICS INPUT IMPEDENCE HIGH INPUT CAPACITANCE IS HIGH INPUT CURRENT IS LOW FANOUT IS LARGE(TYPICALLY 30) LOW OPERATING SPEED PROPAGATION DELAY TIME IS LARGE(50nS) POWER DISSIPATION IS SMALL COMPARED TO TTL (TYPICALLY 0.1mW/GATE)

PMOS TRANSISTORS AS NOR GATE

BASIC CMOS INVERTER

BASIC OPERATION OF CMOS INVERTER

CMOS NAND GATES

CMOS NOR GATE

CMOS AND-OR-INVERT CMOS circuits can perform two levels of logic with just a single level of transistors. Y=

CMOS OR-AND-INVERT Y=

Problem Design CMOS transistor circuit that has functional behaviour f(z)= f(z)= =

Problems Design CMOS transistor circuit that has functional behaviour 1) f(z)= 2) f(z)= 3) f(z)=

CMOS LOGIC LEVELS

CMOS LOGIC LEVELS