Asynchronous and synchronous logic design, Electrical Engineering

Assignment Help:

One of the simplest circuits is the asynchronous or ' ripple' counter. Below is shown the circuit diagram of a simple 3 stage ripple counter.

1234_Asynchronous and Synchronous logic design.png

The operation of this circuit is based on the fact that the truth table for the JK flip flop is only valid if the clock waveform is falling, i.e. 1->0. Assume the outputs are all zero, the flip flops will not change until the clock on each flip flop falls. The clock in waveform has just fallen  ,since the JKa inputs are logic '1' the device will toggle and the output will invert i.e. Qa=1. Flip flop B will not change because the clock waveform on B has risen    (0->1) and these devices only functions on a falling edge. The clock in waveform has fallen again, so Qa toggles again (i.e. Qa =0), this has just produced a falling clock on JKb and Qb toggles (i.e. Qab=1) .The device has just counted from 000-> 001->010.

960_Asynchronous and Synchronous logic design1.png

The circuit is called a ripple counter because the clock pulse is slowly rippling through the JK's, hence asynchronous (Not at the same time!) .The limitations of the asynchronous counter is the speed of operation. A rough formula for the maximum speed is when the clock changes before the output changes i.e.

      F =  1 / n x propagation delay
 
   where n = number of stages, propagation delay of one JK

A better technique is to use a synchronous design where all the JK are clocked together so the maximum frequency is only limited by the propagation delay of 1 JK.  

59_Asynchronous and Synchronous logic design2.png

 
The circuit appears to be complex in design, however it is easily realised by using state diagrams. The maximum frequency of operation is again roughly calculated by considering the frequency at which the output just changes before the clock in changes.
    
      F = 1/ Propagation delay


Related Discussions:- Asynchronous and synchronous logic design

Determine the fault current and the bus voltages, The one line diagram of a...

The one line diagram of a simple three-bus power system is shown in the figure below.  Each generator is represented by an emf behind the transient reactance.  All impedances are e

Flexible manufacturing systems, (a) What are the elements of Flexible Manuf...

(a) What are the elements of Flexible Manufacturing Systems? (b) What are the basic types of workstations typically found in an FMS. Describe them briefly?

Electrons, Ask question #Minimum 100 words accepted how does the charge pla...

Ask question #Minimum 100 words accepted how does the charge plate relate to the movement of electrons

Methods of material handling, Q. Show the Methods of material handling? ...

Q. Show the Methods of material handling? Methods of material handling during operations and maintenance activities shall be considered for all facilities to ensure that the fi

Magnetic ckt''s, what is the difference between statically and dynamically ...

what is the difference between statically and dynamically induced emf''s

Describe the automated flow lines, Describe the Automated flow lines with s...

Describe the Automated flow lines with suitable diagrams? Also provide the Reason for Automating? Discuss the Work part Transfer Mechanisms in detail? Discuss the requirement fo

Program analysis , Program Analysis We have to find the greater of two...

Program Analysis We have to find the greater of two given  number. We  can store the given  numbers  in two  different  registers ( suppose register A and B). Then we will com

Physics, what is the significant of damping coficient

what is the significant of damping coficient

Discuss applications of dielectrics, Discuss applications of dielectrics. ...

Discuss applications of dielectrics. Application of dielectrics: For various applications various properties of dielectric materials are required as: electrical, mechanical

Evaluate the efficiency of embedded systems, Questions: a) One common ...

Questions: a) One common characteristic of Embedded Systems is that they need to be dependable. Name and describe any three aspects which encompass dependability. b) Name

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd