Title DF - 2021W Paper Solution.pdf ✅

DF Winter 2021 Paper Solution Q.1 (a) Implement EX-NOR using NAND gate.  Block Diagram (b) Convert the decimal number 225.225 to octal and hexadecimal. Binary Number  Binary conversion of 225 is (11100001)  0.225 in decimal is equivalent to (.0011100110011001101) in binary  So 225.225 in binary is 11100001.0011100110011001101 Octal Number  The equivalent octal number is  011 100 001.001 110 011 001 100 110 100 3 4 1 . 1 6 3 1 4 6 4
Octal number is (341.1631464)8 HexaDecimal Number  The equivalent hexadecimal number is  1110 0001.0011 1001 1001 1001 1010 E 1 3 9 9 9 A Hexadecimal number is (E1.39)16 (c) Give classification of logic families and compare CMOS and TTL. Logic families are mainly classified as Bipolar Logic Families and Unipolar Logic Families. Bipolar Logic Families: It mainly uses bipolar devices like diodes, and transistors in addition to passive elements like resistors and capacitors. These are sub-classified as the saturated bipolar logic family and the unsaturated bipolar logic family. 1. Saturated Bipolar Logic Family: In this family, the transistors used in ICs are driven into saturation. For example:  Transistor-Transistor Logic (TTL)  Resistor-Transistor Logic (RTL)  Direct Coupled Transistor Logic (DCTL)  Diode Transistor Logic (DTL)  High Threshold Logic(HTL)  Integrated Injection Logic (IIL or I 2 L) 2. Unsaturated bipolar logic family: In this family, the transistors used in IC are not driven into saturation. For example:  Schottky TTL  Emitter Coupled Logic(ECL) Unipolar Logic Families: It mainly uses Unipolar devices like MOSFETs in addition to passive elements like resistors and capacitors. These logic families have the advantages of high speed and lower power consumption than Bipolar families. These are classified as:  PMOS or P-Channel MOS Logic Family  NMOS or N-Channel MOS Logic Family  CMOS Logic Family
 Compare CMOS and TTL CMOS (Complementary Metal-Oxide-Semiconductor) and TTL (Transistor-Transistor Logic) are two different logic families that are commonly used in digital electronic circuits.  Power Consumption: CMOS is known for its low power consumption, making it suitable for battery-powered and low-power applications. TTL, on the other hand, requires a significant amount of power.  Speed: TTL is generally faster than CMOS.  Noise Immunity: CMOS is more sensitive to noise and requires protection against static discharge, while TTL is more robust in this regard.  Voltage Level: TTL uses a 5V power supply to represent the logical states of 0 and 1, while CMOS uses a higher voltage level (typically between 3.3V and 5V)  Fan-out: TTL can handle more loads than CMOS.  Temperature range: TTL can operate in a wider temperature range than CMOS.  Production cost: CMOS is cheaper to produce than TTL. Q.2 (a) Convert F(A,B,C) = BC+A into standard minterm form. (b) With logic diagram and truth table, explain the working of 3 line to 8 line decoder. This decoder circuit gives 8 logic outputs for 3 inputs and has a enable pin. The circuit is designed with AND and NAND logic gates. It takes 3 binary inputs and activates one of the eight outputs. 3 to 8-line decoder circuit is also called a binary to an octal decoder. Logic diagram –