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

Field Service Enginer, Give three reasons why a chamfer shouldn''t an "unim...

Give three reasons why a chamfer shouldn''t an "unimportant" dimension

Basic definition of electromagnetism, Q. Basic definition of electromagneti...

Q. Basic definition of electromagnetism? A basic understanding of electromagnetism is essential to the study of electrical engineering because it is the key to the operation of

Expain different control function categories, Q. Expain different control f...

Q. Expain different control function categories,And also discuss that how they help in signalling and control. Ans: In some switching systems, Control subsystem may be a

Prove modified algorithm better than the elevator algorithm, A slight modif...

A slight modification of the elevator algorithm for scheduling disk requests is to always scan in the same direction, In what respect is this modified algorithm better than the ele

Define voltage divider rule, Define voltage divider rule Voltage drop a...

Define voltage divider rule Voltage drop at every resistor that connected by serial can be search by using voltage divider rules (VDR).

Nand gate - introduction to microprocessors , NAND Gate NAND   means NO...

NAND Gate NAND   means NOT AND  it complements  the output  of an AND  gate. The symbol  of NAND  by a NOT  gate.  Generally Not  operation  is represented by a bubble as shown

Ampliier, importance of amplifier in electronic circuits

importance of amplifier in electronic circuits

Commutation in dc machines, Currents induced in armature conductors of a d....

Currents induced in armature conductors of a d.c. generator are alternating. To make their flow unidirectional in the external circuit, we need a commutator. Moreover, these curren

Describe the process design and application, Disinfection of water streams ...

Disinfection of water streams originating from potable water plants is key in protecting environmental health. Describe the process design and application, along with potential pro

Compute the induced emf, Compute the induced emf: If a coil of 150 tur...

Compute the induced emf: If a coil of 150 turns is linked with a flux of 0.01 wb while carrying a current of 10 Amp, compute the inductance of coil. Now, if current is reverse

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