Class D for ultrasonic!

epilot · 9th July 2011, 02:50 PM

Hello guys,

I need an at least 150W or higher class D amplifier capable of working almost linearity up to 60KHz (the frequency response I expect is from 30KHz to 60KHz). If needed to be mentioned, I do not care of the audio frequencies for it (I.e 20Hz till 20KHz). I do not mind if it works from several Hertz till 60KHz or linearity or just from 30KHz till 60KHz because I want it to drive a big piezo load at ultrasonic range (as already mentioned from 30kHz to 60kHz).
DO you guys kindly know any brand or module to do so please?

Thanks a bunch for any help or suggestion

ViennaTom · 9th July 2011, 05:30 PM

Hello,

I m not sure what your application is. To scare off some mosquitoes, I think it is enough to produce some square wave at these frequencies (i. e. the generator can also be the amplifier for much simpler overall design)...

epilot · 9th July 2011, 05:45 PM

Quote:

Originally Posted by ViennaTom

Hello,

I m not sure what your application is. To scare off some mosquitoes, I think it is enough to produce some square wave at these frequencies (i. e. the generator can also be the amplifier for much simpler overall design)...

Thanks sir,
No mosquitoes repeller I meant!

The system which I want to construct is some kind of imaging system by ultrasonic. It needs a lot of piezo transducers all in parallel to create a very powerful output. The impedance of each transducer is almost 500 ohms, So using 100 of them or even higher will reduce the impedance to less than 5 ohms.
Any way I prefer to use a class D amplifier for this project if possible.

Thannks

ssanmor · 9th July 2011, 06:40 PM

Please keep in touch with us (info@coldamp.com) We have a lot of experience in custom designs.

nigelwright7557 · 09:15 PM

Class d usually has an output filter which will lose the 60KHz.

You might have to buy a class d amp and change the output filter to get it upto 60KHz.

You would also need a class d amp with a high class d frequency to get a good resolution at 60KHz.

theAnonymous1 · 10th July 2011, 03:41 AM

Yes, you need a Class-D design with a >600kHz carrier and an output filter properly calculated for your needs.

For a 5R load 15uH + 500nF will give a Fc of ~58kHz and be will be about -50dB @ 1MHz.

AP2 · 10th July 2011, 08:28 AM

Hi,
I agree with theAnonymous1,
And add: If your signal input is sub-modulated or sin continuos, requires power re-calculation or use a 500w-600w power amplifier for 150w output.
Also, You can add a second outbound filtering, to reduce the residual HF.

Regards
Roberto

ssanmor · 10th July 2011, 12:57 PM

It all depends on your requirements (THD, supply rejection, etc.) It is not only a matter of the output filter.

phase_accurate · 11th July 2011, 06:24 AM

Yes, exactly ! Could you describe what your Signal looks like ? Is it always the same freqency ? The same Level ? Or even both ?

If even only one of these apply then it might be much easier to use an application specific amplifier type.

Regards

Charles

9th July 2011, 02:50 PM	#1
epilot diyAudio Member Join Date: Jul 2006	Class D for ultrasonic! Hello guys, I need an at least 150W or higher class D amplifier capable of working almost linearity up to 60KHz (the frequency response I expect is from 30KHz to 60KHz). If needed to be mentioned, I do not care of the audio frequencies for it (I.e 20Hz till 20KHz). I do not mind if it works from several Hertz till 60KHz or linearity or just from 30KHz till 60KHz because I want it to drive a big piezo load at ultrasonic range (as already mentioned from 30kHz to 60kHz). DO you guys kindly know any brand or module to do so please? Thanks a bunch for any help or suggestion

9th July 2011, 08:55 PM	#5
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	Class d usually has an output filter which will lose the 60KHz. You might have to buy a class d amp and change the output filter to get it upto 60KHz. You would also need a class d amp with a high class d frequency to get a good resolution at 60KHz. __________________ http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software. Last edited by nigelwright7557; 9th July 2011 at 09:15 PM.

10th July 2011, 03:41 AM	#6
theAnonymous1 diyAudio Member Join Date: Feb 2004 Location: Anonymityville	Yes, you need a Class-D design with a >600kHz carrier and an output filter properly calculated for your needs. For a 5R load 15uH + 500nF will give a Fc of ~58kHz and be will be about -50dB @ 1MHz. __________________ "If you don't like funerals don't kick sand in Ninja's face." - Ninja

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9th July 2011, 05:30 PM	#2
ViennaTom diyAudio Member Join Date: Apr 2010	Hello, I m not sure what your application is. To scare off some mosquitoes, I think it is enough to produce some square wave at these frequencies (i. e. the generator can also be the amplifier for much simpler overall design)...

9th July 2011, 06:40 PM	#4
ssanmor diyAudio Member Join Date: Jan 2002 Location: Madrid	Please keep in touch with us (info@coldamp.com) We have a lot of experience in custom designs.

10th July 2011, 08:28 AM	#7
AP2 diyAudio Member Join Date: Dec 2009 Location: Italy	Hi, I agree with theAnonymous1, And add: If your signal input is sub-modulated or sin continuos, requires power re-calculation or use a 500w-600w power amplifier for 150w output. Also, You can add a second outbound filtering, to reduce the residual HF. Regards Roberto

10th July 2011, 12:57 PM	#8
ssanmor diyAudio Member Join Date: Jan 2002 Location: Madrid	It all depends on your requirements (THD, supply rejection, etc.) It is not only a matter of the output filter.

11th July 2011, 06:24 AM	#9
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	Yes, exactly ! Could you describe what your Signal looks like ? Is it always the same freqency ? The same Level ? Or even both ? If even only one of these apply then it might be much easier to use an application specific amplifier type. Regards Charles

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