1

GATE ECE 1988

Subjective

+8

-0

The circuit shown below uses TTL flip-flops. The flip-flops are triggered at the negative transitions of the clock. It is desired that when M = 1 the circuit should function as an up-counter (in 8421 BCD) and when M=0, as a down-counter. Design the combinational circuit interposed between the flip-flops so that the circuit works as desired. (i.e. find F as a function of Q,$$\overline Q $$, M, $$\overline M $$).

2

GATE ECE 1988

Subjective

+8

-0

For the circuit shown in the figure below, sketch V

_{0}against time. Assume that all flip-flops are reset to zero before the clock is applied.3

GATE ECE 1987

Subjective

+8

-0

A 2-input up/down synchrconous counter using two toggle flip-flops is shown in Fig.1. The counter's sequence is to be controlled by the input M as follows:

For M=1, sequence of Q

For M=0, sequence of Q

For M=1, sequence of Q

_{1}, Q_{0}is ..00, 01, 10, 11, 00, 01.......For M=0, sequence of Q

_{1}, Q_{0}is ..00, 11, 10, 01, 00, 11......(a)Design the necessary feedback logic for T_{1} and T_{0}.

(b)Realize the feesback logic using inverters and 4-input multiplexers only. Use Q_{1} and Q_{0} as the control inputs of the multiplexer with Q_{1} as the MSB.

Questions Asked from Sequential Circuits (Marks 8)

Number in Brackets after Paper Indicates No. of Questions

GATE ECE Subjects

Signals and Systems

Representation of Continuous Time Signal Fourier Series Fourier Transform Continuous Time Signal Laplace Transform Discrete Time Signal Fourier Series Fourier Transform Discrete Fourier Transform and Fast Fourier Transform Discrete Time Signal Z Transform Continuous Time Linear Invariant System Discrete Time Linear Time Invariant Systems Transmission of Signal Through Continuous Time LTI Systems Sampling Transmission of Signal Through Discrete Time Lti Systems Miscellaneous

Network Theory

Control Systems

Digital Circuits

General Aptitude

Electronic Devices and VLSI

Analog Circuits

Engineering Mathematics

Microprocessors

Communications

Electromagnetics