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

Working out the function of a combination of gates, Working out the functio...

Working out the function of a combination of gates? Truth tables are able to be used to work out the function of a combination of gates. Inputs Outputs

project, I want to make project plz help me n gove me idea about actually ...

I want to make project plz help me n gove me idea about actually its my first year in electrical engineering thts why Ineed help hpfully you will reply soon

Rise time - power semiconductor devices , Rise  Time (t r ) During  ri...

Rise  Time (t r ) During  rise time voltage falls from 90% V a to 10%  where  V a where V a is the initial  anode  voltage. In terms  of current  time taken  by anode  curre

What do you understand by bezier surface, What do you understand by Bezier ...

What do you understand by Bezier surface ? Discuss Determine the equivalent bicubic formulation of a closed and open cubic B-spine surface. a) What do you understand by solid

Show quantization error, Quantization Error Sampling followed by quanti...

Quantization Error Sampling followed by quantization is equivalent to quantization followed by sampling. Figure illustrates a message signal f (t) and its quantized version den

Sommerfield’s free electron theory, Write down basic postulates of sommerfi...

Write down basic postulates of sommerfield’s free electron gas model. Show that the number of energy states per unit energy is given by g(E) = 4Rv/h 3 (2m) 3/2 E 1/2 .  What is

Determine the Service and Backwash Rates, Determine the Service and Backwas...

Determine the Service and Backwash Rates The system on site is a pressure sand filter, with a service curve. The filter is backwashed using the feed pump, at a higher flow rate, s

Hybrid model for two-port network, Hybrid Model for Two-port Network:- ...

Hybrid Model for Two-port Network:-             V 1 = h 11 i 1 + h 12 V 2                                                                             I 2 = h 1 i 1

Basic introduction of analog building blocks, Q. Basic introduction of Anal...

Q. Basic introduction of Analog Building Blocks? Electronic systems usually process information in either analog or digital form. In order to process the two different kinds of

Calculate the generator emf , Q.  The armature of 6 -pole dc generator has...

Q.  The armature of 6 -pole dc generator has a wave winding containing 664 conductors. Calculate the generator emf when flux per pole is 0.06 weber and the speed is 250 rpm. At wh

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