Earlier I posted some test results for AD SAR ADC.
Follow the same procedure, I put mcp3562 on my test bench as DUT this time. To my surprise, SD adc shows astonishingly good results.
Sampling rate 62.5 kHz. FFT-32k, test tone 2kHz (there is an inaccuracy on TFT screen, it reflects 1kHz for 31.25 ksps).
MCP356X Linearity test. - YouTube
Waiting pcm4202 to compare with, my promised by Friday delivery was delayed.
Stay tuned.
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31-08-2021 Updates:
Code mcp356X_h743zi2_forum_5dx.zip - Google Drive
I have no plans to develop this project, harry up if you have any questions regarding to code, till my Alzhemer hits me hard 🙂
Follow the same procedure, I put mcp3562 on my test bench as DUT this time. To my surprise, SD adc shows astonishingly good results.
Sampling rate 62.5 kHz. FFT-32k, test tone 2kHz (there is an inaccuracy on TFT screen, it reflects 1kHz for 31.25 ksps).
MCP356X Linearity test. - YouTube
Waiting pcm4202 to compare with, my promised by Friday delivery was delayed.
Stay tuned.
****************************
31-08-2021 Updates:
Code mcp356X_h743zi2_forum_5dx.zip - Google Drive
I have no plans to develop this project, harry up if you have any questions regarding to code, till my Alzhemer hits me hard 🙂
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I see -8dB for the main tone, -126dB for the 3rd harmonic, a difference of 118dB and the specs for the MCP3562 say THD is typically -116dB for the first ten harmonics.
Not exactly unexpected from the specs, quite nice to see of course! I note the THD performance drops like a stone if you don't select gain=1.
I think that distortion figure is only for 50Hz tone, not clear if the performance is retained at higher frequencies.
Not exactly unexpected from the specs, quite nice to see of course! I note the THD performance drops like a stone if you don't select gain=1.
I think that distortion figure is only for 50Hz tone, not clear if the performance is retained at higher frequencies.
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Digital table in dBc, means data already corrected for -7.5dB main tone. Not 50Hz, but 2kHz. My quick estimation for 10kHz is also very good, there only issue that to do it right, sampling has to be pushed up to 125 kHz , though OSR - oversampling ratio would be x32 and with such low value I see significant rising of noise. Another complication I'm not sure my SG can be trusted to -130dB HD-2 & 3 at high frequency end. AD7693 I verified my setup with is not doing well at 10k and up.
I will retest at 10k vs pcm4202 when I get one.
I will retest at 10k vs pcm4202 when I get one.
As promised, here is linearity results for PCM4202 by TI.
First things to mention, it's "comparative" test.
Thats means, I use the same adapter boards, more or less similar size and types of the capacitors,
identical preamplifier and the same SG. Technicaly speacking audio codec
was evaluated in the "hobbyst" grade enviroment, w/o 4-layers PCB and 180MHz
diff preamp recommended by manufacturer. Preamp LME49721 was running at relaxing 5V power line for
PCM4202, and at more tough +3.3V with MCP3562.
Microchip is a winner. Only excuse for looser that it was designed 2 decades ago.
Again, freq. scale in the video is off - 2 kHz sharp in both cases, 2.87 due
sampling rate 62.5 /2.87 = 21.77kHz.
PCM4202 linearity test, Dual mode, I2S slave.
pcm4202 62 5kHZ - YouTube
pcm4202 22kHz - YouTube
First things to mention, it's "comparative" test.
Thats means, I use the same adapter boards, more or less similar size and types of the capacitors,
identical preamplifier and the same SG. Technicaly speacking audio codec
was evaluated in the "hobbyst" grade enviroment, w/o 4-layers PCB and 180MHz
diff preamp recommended by manufacturer. Preamp LME49721 was running at relaxing 5V power line for
PCM4202, and at more tough +3.3V with MCP3562.
Microchip is a winner. Only excuse for looser that it was designed 2 decades ago.
Again, freq. scale in the video is off - 2 kHz sharp in both cases, 2.87 due
sampling rate 62.5 /2.87 = 21.77kHz.
PCM4202 linearity test, Dual mode, I2S slave.
pcm4202 62 5kHZ - YouTube
pcm4202 22kHz - YouTube
I'm impressed with what you are getting from this setup. I don't see any current efforts towards a stand alone audio band spectrum analyzer like the DSO's. What does it take to reproduce what you are building? Is the software existing or built from scratch?
My curiosity push me to buy AD evaluation module AD7988-5 ( ~$30 CAD ) a couple years ago.
Having properly designed board from chip maker is certanly great advantage.
Combining adc with nucleo-H743 I build my my first 250 kHz SA.
Than I tested AD7984, AD7983, AD7693 & AD7982. Try nucleo-F446 & F767.
Idea to compare ADC between major players come later, but unfortunately,
evaluation modules from TI or Microchip are too expensive to play with.
Though, indeed it's impressive to see -120dBc in such low profile environment.
Seems to me like Microchip doesn't take money from board manufacturers,
and doesn't tweak ADC to run on 4+ layers PCB only.
Software is my own, Arduino IDE and Adafruit TFT library save me a lot of time,
and greatly simplified this project series development.
If someone want to reproduce - get yourself mcp3561R & nucleo-H743zi2 from mouser,
TFT from aliexpress or amazon. I will share software pack uploading here
or on google-drive.
Having properly designed board from chip maker is certanly great advantage.
Combining adc with nucleo-H743 I build my my first 250 kHz SA.
Than I tested AD7984, AD7983, AD7693 & AD7982. Try nucleo-F446 & F767.
Idea to compare ADC between major players come later, but unfortunately,
evaluation modules from TI or Microchip are too expensive to play with.
Though, indeed it's impressive to see -120dBc in such low profile environment.
Seems to me like Microchip doesn't take money from board manufacturers,
and doesn't tweak ADC to run on 4+ layers PCB only.
Software is my own, Arduino IDE and Adafruit TFT library save me a lot of time,
and greatly simplified this project series development.
If someone want to reproduce - get yourself mcp3561R & nucleo-H743zi2 from mouser,
TFT from aliexpress or amazon. I will share software pack uploading here
or on google-drive.
More on topic, evaluation of the 24-bits SD ADC. MAX11270 this time. In short, compare to MCP3561R series:
a) higher noise at 62.5 ksps, Because of this issue, I can't do the same 2 kHz tone test, have to build another ultra low THD
signal source for 200 Hz. Sampling 4 ksps, frame rate about 8 sec (!) - with FFT-32k.
b) linearity is better at least 5dB for both hd-2 & hd-3, running "parallel" sampling - I soldered 2 exactly the same units. Both based on
stm 32 H743 Zi2 , same TFT and power modules, almost same type of caps and resistors etc.
a) higher noise at 62.5 ksps, Because of this issue, I can't do the same 2 kHz tone test, have to build another ultra low THD
signal source for 200 Hz. Sampling 4 ksps, frame rate about 8 sec (!) - with FFT-32k.
b) linearity is better at least 5dB for both hd-2 & hd-3, running "parallel" sampling - I soldered 2 exactly the same units. Both based on
stm 32 H743 Zi2 , same TFT and power modules, almost same type of caps and resistors etc.