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Dear community,
For my internship, I am interested in the maximum streaming rate when using a Delta Sigma ADC to read an input and output it using a VDAC. The actual signal that will be used for the control algorithm will also have to be filtered, which might introduce more delay than I am already experiencing. Moreover, the signal will be around 80 kHz.
During testing, I saw that a sinusoidal signal of 50 kHz already has quite some phase delay with respect to the original signal, when it is outputted to using a VDAC. Is this just the limit of the PSOC5 I am using? Or am I missing some things that might give me better performance? For reference on what I did, see the figures below (yellow is signal generator, blue is VDAC). Also, the project has been attached.
With kind regards,
Jim
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PSoC 5LP
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Jim,
I see 4 clocks delay between the input and output. Somewhere in the DelSigADC's datasheet is mentioned that it needs 4 clocks to "prime".
Since the output (VDAC8) is already 8bit, try to reduce ADC's resolution to 8bit and rise sampling frequency to the max to improve frequency response.
Due to intgrating nature of DelSigADC, there will always be a delay. It's intended frequency domain is <20kHz. For 100+kHz domain consider using SARADC.
/odissey1
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Jim,
I see 4 clocks delay between the input and output. Somewhere in the DelSigADC's datasheet is mentioned that it needs 4 clocks to "prime".
Since the output (VDAC8) is already 8bit, try to reduce ADC's resolution to 8bit and rise sampling frequency to the max to improve frequency response.
Due to intgrating nature of DelSigADC, there will always be a delay. It's intended frequency domain is <20kHz. For 100+kHz domain consider using SARADC.
/odissey1
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Dear Odissey1,
Thank you for the response! I will take a closer look into the SARADC for my application.
With kind regards,
Jim
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Jim,
according to the Datasheet, in 16bit continuous sampling mode, the max sampling rate is 48kHz, but the bandwidth is only 11kHz (~1/4). I suspect that is what you observe. Switch to 8bit mode and use 384 kHz sampling rate.
Also turn off input buffer to see any effect on delay.