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 briefly subscriber loop system, Q. Determine briefly subscriber l...

Q. Determine briefly subscriber loop system.  Give some technical specification for subscriber lines. Ans: Subscriber Loop System: Each subscriber in a telephone network is

Find the t-domain forced response in glc parallel circuit, Consider a GLC p...

Consider a GLC parallel circuit excited by i(t) = Ie st in the time domain. Assume no initial inductive current or capacitive voltage at t = 0. Draw the transformed network in the

Guidelines from electricity regulatory commission, Guidelines from Electric...

Guidelines from Electricity Regulatory Commission The electricity companies have successfully adopted the guidelines issued through ERCs Utilities usually set their yearly KP

Comparison between motorola processors and intel processors, Differentiate ...

Differentiate between Motorola processors and INTEL processors. Comparison between Motorola processors and INTEL processors: AMD/Intel processors are actually about similar t

For the low-pass filter configuration calculate cf, Q. For the low-pass fil...

Q. For the low-pass filter configuration of Figure, with R i = R f = 1M, calculate C f such that the 3-dB point is at 1 kHz.

Briefly explain about wheatstone bridge, Q. Briefly explain about Wheatston...

Q. Briefly explain about Wheatstone Bridge? Null measurements are made with bridge circuits and related configurations. They differ from direct measurements in that the quantit

Direct addressing , Direct Addressing In this  addressing  mode one  o...

Direct Addressing In this  addressing  mode one  of the  operands is the  data stored  in the memory. The memory  address of the  operand is directly  given in the instruction

Explain einstein relation, Explain Einstein relation. Einstein relation...

Explain Einstein relation. Einstein relation: There exists a significant relation between the diffusion constant and the mobility. It is termed as the Einstein relation and

What are tightly coupled systems, What are tightly coupled systems or close...

What are tightly coupled systems or closely coupled systems? In a tightly coupled systems the microprocessor (either coprocessor or independent processors) might be share a com

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