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

Standard deviation of mean, For large number of measurements the mean is ca...

For large number of measurements the mean is calculated by taking a sample. Each sample that is taken has a mean. The mean of various sample difference from sample and are known to

determine the minimum dandwidth of the system - fsk and ask, 1. Data is to...

1. Data is to be transmitted using a modem at 9600 bps. Determine the minimum bandwidth of the system with the following modulation methods (a) FSK (b) ASK. Use the excess

Network topology, LAN topologies: Network topology is a physical schematic...

LAN topologies: Network topology is a physical schematic that demonstrates interconnection of the many users. There are four fundamental topologies as under: (i) Direct Connect

Design an electro-pneumatic system, (i) Sketch a fully-labelled electro-pne...

(i) Sketch a fully-labelled electro-pneumatic circuit showing your actuators in the START position and employ metered out speed control with mono-stable 5/2 DCV's having solenoid a

Active-mode npn transistors in circuits, Active-mode NPN transistors in cir...

Active-mode NPN transistors in circuits Figure:  Structure and use of NPN transistor. Arrow according to schematic. The figure opposite is a schematic presentation

Differences between a timer and a counter, Question : a) Embedded Syste...

Question : a) Embedded Systems will be Hard Real-Time Systems, Soft Real-Time Systems and Hybrid Real-Time Systems. Briefly explain all three types of Real-Time Systems, using

Butterworth filter, what is experimental setup for Butterworth filter?

what is experimental setup for Butterworth filter?

Give homogeneous matrix quation for b-splive curve, What are the different ...

What are the different kinds of surface entities used in CAD? Give homogeneous Matrix form equation for : (i) B-Splive Curve (ii) Bezier Curve

1- phase full bridge inverter with r- load , 1- phase  Full Bridge Invert...

1- phase  Full Bridge Inverter with R- Load 1-phase full  bridge inverter with resistive load R i it has  advantage over 1-? half  bridge  inverter that it does  not require

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