signal

[yyy]

How can I convert square signal to sin signal ?
Also I need that it will fit to wide frequency range
Why in resonance circuit the convert frequency is only for one specific frequency?

[billhowl]

It can be done with two stages of integrators, the first one converts the square wave to a triangle wave, and the second stage converts the triangle wave to a sine wave. If the input frequency varies widely then the output amplitude will vary.
Here is a typical schematic, two identical stages are required

A Quick Sine Wave Generator
http://www.national.com/nationaledge/jun04/article.html

[Soeren]

Hi,

How can I convert square signal to sin signal ?
Also I need that it will fit to wide frequency range

How wide?

Can be done in several ways - a PLL controlling a DDS Sine generator would be my choice.

[yyy]

Thanks billhowl & soeren
Soeren, what do you main in PLL controlling ?
Can you explain it ?

[Soeren]

Hi,

Soeren, what do you main in PLL controlling ?
Can you explain it ?

PLL = Phase Locked Loop.
DDS = Direct Digital Synthesis

The PLL looks at both the output from the DDS and your square wave signal and "locks" the two together.
If the signal drifts/deviates, the PLL will correct it,
The output from a DDS can be anything you can imagine, sine, triangle, saw tooth or something entirely different, like the quack of a duck

What's your purpose with the converted signal?