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# How can i convert square wave to sinewave of same frequency? - RF Cafe Forums

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Below are all of the forum threads, including all the responses to the original posts.

khalil_cse@yahoo.com
Post subject: How can i convert square wave to sinewave of same frequency?
Unread postPosted: Sun Mar 20, 2005 2:20 am

Hi
Anybody can help me to design a circuit to convert square wave to sine wave of same frequency to build local oscillator for radio card.
khalil

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Guest
Post subject:
Unread postPosted: Sun Mar 20, 2005 9:40 am

If you perform a Fourier Series of a square wave you will see that it is made up of multiple frequencies, in particular, high frequency components. Therfore, to convert a square wave to a sine wave, you simply filter out the higher order components by using a low pass filter that will pass the frequency of the square wave (1/period) and reject the higher order components.

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chaitanya
Post subject: need the same help as u need
Unread postPosted: Tue Apr 12, 2005 4:13 am

If u get pls forward to saichaitanya@indiatimes.com..thanks..and pls

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Guest
Post subject: Square to Sine for LO
Unread postPosted: Mon Apr 18, 2005 10:07 pm

Actually, most of the time you want your mixer to act as a switch, rather than as a linear multiplier. This is the reason for running standard diode double balanced mixers at the rated power (+7/17/27dBm) - to get good switching action. This gives you better 3rd order intercept performance, for example.

What frequency range are you looking at? A low pass filter only works if you have somewhat less than a 3:1 frequency range. People have used tunable bandpass filters (such as those made by Pole-Zero Corp) to cover wider ranges.

Good Luck!

Posted  11/12/2012
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