What is the difference between CLK and square wave?

[fidelity]

CLK and square wave

Whats a exact difference in CLK and square wave

 

[banjo]

CLK and square wave

This is a very broad question. In the most general case, there is no real difference. A square wave implies a 50% duty cycle. It is possible to create a digital clock signal that does not have a 50% duty cycle, so in that case they would be different.

On very high speed logic, it is doubtful that even a 50% duty cycle clock is really a sqaure wave. A true mathematical square wave requires infinitely steep rise times and perfectly flat tops. To achieve this requires an infinite number of harmonics. High speed system cannot handle anywhere near even the tenth harmonic of a high speed clock. Therefore, if you look at these clocks on a scope, they appear more like sine waves rather than square wave clocks. The waves are so mis-shapen now that it could cause major timing inconsistencies in high speed logic. The solution is to use two out of phase clocks in a differential pair. In this case, it is not important when a clock with a limited rise time crosses an arbitrary level. Rather, it is only important when the two out of phase clocks cross each other.

Describing clocks as square waves is really only in textbooks now. In real life, the ideal square wave never exists.

 

[jal_rule]

CLK and square wave

go for banjo!!!i wonder you have the time to explain it.
for the simplest, yeah man it look a like. clock is the square wave needed to drive the device.but still you need to study its clock requirement (it timing dude!!) and its explained in time diagram on every device datasheet!!.