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

Explain the term telecommunication, Question 1 Explain the term telecommun...

Question 1 Explain the term telecommunication and how its implied meaning has changed over time and outline major developments in telecommunication technologies Question 2

Determine the expression for strain energy, A 3.2m long bar of 16mm in diam...

A 3.2m long bar of 16mm in diameter hangs vertically and has a collar attached at the lower end calculate the max. stress induced when a weight of 80 kg falls fromaheight of 32mm o

Asynchronous message passing and synchronous-message passing, Question: ...

Question: a) Differentiate between Asynchronous message passing and Synchronous-message passing. b) If keyboards are the predominant means of interface to human input, the

Evaluate hysteresis loss, Q. A magnetic circuit is found to have an ac hyst...

Q. A magnetic circuit is found to have an ac hysteresis loss of 10 W when the peak current is Im = 2 A. Assuming the exponent of Bm to be 1.5, estimate Ph for Im = 0.5A and 8A.

Draw a state diagram of 3-bit ripple counter, The block diagram for a 3-bit...

The block diagram for a 3-bit ripple counter is shown in Figure (a). Obtain a state table for the number of pulses N = 0 to 8, and draw a state diagram to explain its operation.

Determine the regulation of three-phase, A three-phase, six-pole, wye-conne...

A three-phase, six-pole, wye-connected synchronous generator is rated at 550 V and has a synchronous reactance Xs = 2 . When the generator supplies 50 kVA at rated voltage and a p

Relationship between the induced e.m.f and the network, Mathematical relati...

Mathematical relationship between the induced e.m.f and the network Faraday noted that the e.m.f induced in a loop is proportional to the rate of change of magnetic flux by it:

Explain fourth group of 32 ascii character code, Explain Fourth group of 32...

Explain Fourth group of 32 ASCII character code? The fourth, and final, group of 32 ASCII character codes are set aside for the lower case alphabetic symbols, five additional

Obtain a thevenin equivalent circuit, Q. (a) Obtain a Thevenin equivalen...

Q. (a) Obtain a Thevenin equivalent circuit at terminals A-B in the circuit. (b) What impedance ¯ZL, when connected to A-B, produces maximum power in ¯ZL? (c) Find the val

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