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28th May 2019, 15:37 #21
Re: How can I generate Sine wave from any periodic waveform that has low frequency?

28th May 2019, 15:39 #22

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28th May 2019, 16:03 #23
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Re: How can I generate Sine wave from any periodic waveform that has low frequency?
carrier frequency implies some sort of modulation.
   Updated   
If I want a 10kHz sine wave, by Nyquist criteria, 25kHz to 30kHz should be my filter's cutoff frequency, right? It is not carrier frequency.
That's easily achieved in the digital domain with audio filters. But an analog output filter for a classD amplifier suggests larger ratios.
As I don't apply to design the application for you (I guess neither other Edaboard members), I suggest that you start to do calculations on your own.
the power amplifier's gate driver signal comes from FPGA.

28th May 2019, 17:29 #24

28th May 2019, 17:58 #25

28th May 2019, 18:43 #26
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Re: How can I generate Sine wave from any periodic waveform that has low frequency?
Hi,
http://lmgtfy.com/?q=Switched+Capacitor+%20Filter+IC
even on the first page I see a couple datsheets of devices from different manufacturers and documents explaining the function....
What else do you need?
KlausPlease don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.

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28th May 2019, 20:19 #27
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Re: How can I generate Sine wave from any periodic waveform that has low frequency?
The switched capacitor filter IC I used a long time ago is obsolete now and not made anymore. Maxim have some today.

28th May 2019, 22:37 #28

28th May 2019, 22:54 #29
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Re: How can I generate Sine wave from any periodic waveform that has low frequency?
Filtering a square wave with a switched capacitor or other low power filter implies that you have an analog power amplifier to generate the specified output. In this case, it would be much easier to use an oversampling audio DAC as signal generator.
   Updated   
Doesn't change much for the hardware requirements. You want sine of arbitrary frequency, DAC is an universal hardware solution.

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29th May 2019, 02:26 #30
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Re: How can I generate Sine wave from any periodic waveform that has low frequency?
I think a square wave of frequency f (say 10kHz) will have sine wave components of f, 3f, 5f, 7f....Odd harmonics!
A square wave of 50% duty cycle has some symmetry and because of that even components (even harmonics) disappear.
But if you have a pulse sequence that have 40% (something not equal to 1/2) duty cycle, the symmetry disappears. Then you will have all the frequencies.
A small deviation from the 50% symmetry can cause these even harmonics to appear.

29th May 2019, 02:51 #31

3rd June 2019, 06:12 #32
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Re: How can I generate Sine wave from any periodic waveform that has low frequency?
By definition a square wave has 50% duty cycle. Any other duty cycle wave would be called Pulse wave or rectangular wave.
Just saying.
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3rd June 2019, 12:32 #33
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Re: How can I generate Sine wave from any periodic waveform that has low frequency?
you might consider a peaking butterworth low pass filter
Sallen Key style
set Q about 8 or 10, let R1 = R2 and C1 = C2,
one opamp, 2 resistors, 2 capacitors and bypass capacitors
net result is your 10 kHz signal since the 10 kHz square wave input has no lower frequency components

3rd June 2019, 15:37 #34
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Re: How can I generate Sine wave from any periodic waveform that has low frequency?
Second order Butterworth has Q=0.71 and monotonous magnitude response by definition. Q=8 corresponds to Chebyshev with about 18 dB ripple.
In any case the solution is far from the original requested 0  10 kHz frequency range, but may be it's not so serious.
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