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

Zener Diode, #question ...THE APPLICATION AND OPERATION OF ZENER DIODES

#question ...THE APPLICATION AND OPERATION OF ZENER DIODES

Define permanent magnet, Define permanent magnet A permanent magnet is ...

Define permanent magnet A permanent magnet is a piece of ferromagnetic material (like as iron, nickel or cobalt) which has properties of attracting several pieces of these mater

Dc motor, You have been given a DC motor to characterize. What three measu...

You have been given a DC motor to characterize. What three measurements are required in order to develop the torque-speed curve and the acceleration curve for the unloaded motor?

Block diagram convert into Electrical Circuit, i have block diagram and i n...

i have block diagram and i need to convert it into Electrical circuit and on electrical circuit need to apply state space method.

Find the power supplied by the voltage source, Find the power supplied by t...

Find the power supplied by the voltage source and the power absorbed by the 24 Ω resistor (R3) in the circuit shown below:   Determine the voltage V2 in the circuit shown.

How clock signal is generated in 8086, How clock signal is generated in 808...

How clock signal is generated in 8086?what is the maximum internal clock frequency of 8086? Clock input 33% square wave from external clock generator .the external clock genera

What do you maen by debugger, What do you maent by Debugger? Debugger:...

What do you maent by Debugger? Debugger: This is a program that allows user to debug and test programs. All computers with microprocessor kits give debugging facility. To not

Bode plot, Hai.. i have been given a open loop transfer function to draw a...

Hai.. i have been given a open loop transfer function to draw a bode plot with a particular K value and they asked me to find the value of K for which the phase margin becomes 45d

Describe the design procedure of oai 321 cell at transistor, Obtain express...

Obtain expressions for the drain source current in an n-channel MOS transistor in terms of terminal voltages and transistor parameters. Indicate reasons why, for deep sub micron t

Explain sahf instructions in 8086 family, Explain SAHF instructions in 80...

Explain SAHF instructions in 8086 family with example and their effect on flag. SAHF: Store AH register in flag register, this is an instruction utilized to store the data i

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