Recent content by Marvin

  1. M

    New face in op amp industry

    This was posted on Khadas forum with a note that it's a Japanese manufacturer:
  2. M

    Review and Measurements of WesionTEK Khadas Tone Board DAC

    Nothing wrong with the I/V stage, good engineering all around. About the schematics:
  3. M

    Review and Measurements of WesionTEK Khadas Tone Board DAC

    Thanks bbt8888! Those TI application notes are really good read for anyone interested in electronic design on DACs! I'll link them in: http://www.ti.com/lit/an/sbaa333/sbaa333.pdf http://www.ti.com/lit/an/sboa237/sboa237.pdf
  4. M

    Review and Measurements of WesionTEK Khadas Tone Board DAC

    It's interesting biasing indeed. On my over-simplified-schematic had it marked as 3.3V but that's the AVCC_R rail, in reality it goes thru a resistor divider with 10k/3.3k ohm so the bias on the non-inverting input of RT6862D is 0.82V. The output from ES9038Q2M is a differential signal with zero...
  5. M

    Review and Measurements of WesionTEK Khadas Tone Board DAC

    I can't make it more clear so I drew a new picture what RED markings mean on the schematic. They are "BUS" or "SIGNAL" markings and mean a single connections. Here is how it looks on the official schematic: EDIT: I thought how to visualise it even another way. Here is how it looks on a more...
  6. M

    Review and Measurements of WesionTEK Khadas Tone Board DAC

    The schematic makes more sense when it's drawn out and not split to pieces. The official schematic is "a professional view" and one has to follow the singal markings. Sorry for the crudeness, but here is my quick redraw of it with only the interesting components marked (and signal names to...
  7. M

    Review and Measurements of WesionTEK Khadas Tone Board DAC

    There is no OPA1612 on the board. The output stage consists of 100% NDA (no datasheet or specifications available) opamps that are produced by ESS and sold as part of a complete ES9038Q2M DAC design. In essence this is implemented on the Khadas board with really great PCB design to complement...
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