Near perfect accuracy 16bit DAC idea

Bernhard · 10th May 2004, 07:44 PM

Hi,

I know how to reach extremely high accuracy in 16 bit conversion.

It is really possible, but not for DIYers.

dhaen · 10th May 2004, 08:05 PM

How?

Bernhard · 10th May 2004, 08:35 PM

How ?

Some big company will make big $$$ and we will not be able to afford it

How could we avoid that ?

dhaen · 10th May 2004, 09:17 PM

If they want to make big $$$, it must be made affordable

till · 10th May 2004, 09:20 PM

go to patent lawyer - or send a kid from your family to "invent a chip"

Bernhard · 10th May 2004, 09:47 PM

Calibration:

Take a 20bit DAC chip.
Measure the output voltage with a 6,5 digit DVM.
Calculate the theoretical output voltage of an ideal 16bit DAC for a 16 bit data code.
Measure which 20 bit data code gives closest match to theoretical 16bit value in output voltage on the 20bit DAC.
Store this 20bit code in eprom.

Do this with all possible 16bit data codes.

DAC:

Convert seriell data to parallel data, feed it to eprom adress input, read eprom data, convert it to seriel, feed 20bit DAC.

The 16bit data now is converted by the eprom to a 20bit data that very closely matches the exact value.

Next step:

This procedure could be used to eliminate distortion in non feedback amplifiers.

Instead of measuring output of 20bit DAC output of amp is measured.

Amplitude error correction is stored in the eprom.

till · 10th May 2004, 09:51 PM

why cant this be done diy?

Bernhard · 10th May 2004, 09:57 PM

Ok,

do it for us.

65000 codes have to be stored in the eprom, 1000000 measurements have to be done and selected from

Another more simple thing could be to add 4 zeros to a 16bit data word and send that to a 20bit DAC.

I tried to swap PCM56 for PCM61, does not work, sound is distorted.

till · 10th May 2004, 10:13 PM

Quote:

65000 codes have to be stored in the eprom, 1000000 measurements have to be done and selected from

it may be better to find a funktion to do correction than storer in an eprom. Or if every value should be stored a SRAM. And the measurement a dsp could do at power up of the device, store the values, and compute them with the signal.

Bernhard · 10th May 2004, 10:19 PM

Unfortunately every chip is different.

So no function can be found.

6,5digit DVMs are still very expensive.

Do you think that can be implemented in the chip ???

10th May 2004, 07:44 PM	#1
Bernhard diyAudio Member Join Date: Apr 2002 Location: Munich	Near perfect accuracy 16bit DAC idea Hi, I know how to reach extremely high accuracy in 16 bit conversion. It is really possible, but not for DIYers.

10th May 2004, 08:05 PM	#2
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	OK, I bite... How?

10th May 2004, 09:47 PM	#6
Bernhard diyAudio Member Join Date: Apr 2002 Location: Munich	Let me know what you think Calibration: Take a 20bit DAC chip. Measure the output voltage with a 6,5 digit DVM. Calculate the theoretical output voltage of an ideal 16bit DAC for a 16 bit data code. Measure which 20 bit data code gives closest match to theoretical 16bit value in output voltage on the 20bit DAC. Store this 20bit code in eprom. Do this with all possible 16bit data codes. DAC: Convert seriell data to parallel data, feed it to eprom adress input, read eprom data, convert it to seriel, feed 20bit DAC. The 16bit data now is converted by the eprom to a 20bit data that very closely matches the exact value. Next step: This procedure could be used to eliminate distortion in non feedback amplifiers. Instead of measuring output of 20bit DAC output of amp is measured. Amplitude error correction is stored in the eprom.

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10th May 2004, 08:35 PM	#3
Bernhard diyAudio Member Join Date: Apr 2002 Location: Munich	How ? Some big company will make big $$$ and we will not be able to afford it How could we avoid that ?

10th May 2004, 09:17 PM	#4
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	If they want to make big $$$, it must be made affordable

10th May 2004, 09:20 PM	#5
till Banned Join Date: Apr 2002 Location: Germany, Clausthal	go to patent lawyer - or send a kid from your family to "invent a chip"

10th May 2004, 09:51 PM	#7
till Banned Join Date: Apr 2002 Location: Germany, Clausthal	why cant this be done diy?

10th May 2004, 09:57 PM	#8
Bernhard diyAudio Member Join Date: Apr 2002 Location: Munich	Ok, do it for us. 65000 codes have to be stored in the eprom, 1000000 measurements have to be done and selected from Another more simple thing could be to add 4 zeros to a 16bit data word and send that to a 20bit DAC. I tried to swap PCM56 for PCM61, does not work, sound is distorted.

10th May 2004, 10:19 PM	#10
Bernhard diyAudio Member Join Date: Apr 2002 Location: Munich	Unfortunately every chip is different. So no function can be found. 6,5digit DVMs are still very expensive. Do you think that can be implemented in the chip ???

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