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

Tardy billing and poor revenue collection, Tardy Billing and Poor Revenue C...

Tardy Billing and Poor Revenue Collection Prolonged disputes, connivance, lack of consumer friendly policies, incorrect identification of category, fictitious billing (of non-

What is the function of dma address register, What is the function of DMA a...

What is the function of DMA address register? Every DMA channel has one DMA address register. The function of this register is to keep the address of the starting memory locati

Estimate the change in hysteresis loss, (a) Estimate the hysteresis loss at...

(a) Estimate the hysteresis loss at 60 Hz for a toroidal (doughnut-shaped) core of 300-mm mean diameter and a square cross section of 50mmby 50mm. The symmetrical hysteresis loop f

Biasing the bjt, Q. Biasing the BJT? A simple method of biasing the BJT...

Q. Biasing the BJT? A simple method of biasing the BJT is shown in Figure. While no general biasing procedure that will work in all cases can be outlined, a reasonable approach

What is elementary diode circuits, Q. What is Elementary Diode Circuits? ...

Q. What is Elementary Diode Circuits? Semiconductor diodes are used in a wide variety of applications. Their usage abounds in communication systems (limiters, gates, clippers,

Floor number display, It is required that the current floor position be dis...

It is required that the current floor position be displayed as a number 1, 2, or 3 on a seven segment LED display on floor 1, which is quite close to the LCU. Data Storage It

Construction of a two stage rc coupled amplifier, Q. Describe the construct...

Q. Describe the construction of a two stage RC coupled amplifier with diagram. A cascaded arrangement of common-emitter transistor stages is shown above. The output Y1 of

Op-amp amplifier, A voltage signal generated by a sensor conditioning circu...

A voltage signal generated by a sensor conditioning circuit varies from -0.5V to +0.5V . The signal from the sensor is to be connected to the analog to digital  converter which onl

Find the voltage drop and current through each component, A 15 volts source...

A 15 volts source is applied to a series 150 μH inductor and 169 pF capacitor. The resistance of the inductor plus the connecting wires is 1,6 Ω. Determine the voltage drop and

Determine the range of the step size, 1. (a) Consider a sinusoidal signal m...

1. (a) Consider a sinusoidal signal m(t) = A cos(2 Π f m t) applied to a delta modulator with step size . Determine the range of the step size so that slope overload will be avoide

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