September 24, 2011

QuantAsylum QA100 Oscilloscope Teardown

Filed under: Uncategorized — engineeringtopics @ 8:04 pm

In the last post I looked at the overall PCB of the QA100. In this post I wanted to look more at the individual parts. Recall the main PCB below:

On the left are the BNC inputs and the analog section, and in the middle are the digital pieces. The problem with scratching off part numbers is that it’s a manual task, and you never get it all. And various bloggers putting the pieces together will figure it out piece by piece.

This is the front end. Looks like the BNC input goes through a low freq DC switch (DIP part) to select AC or DC coupling, and then after that its a resistive divider and into a (likely) JFET op-amp.

This op-amp part is followed by an AD part marked “MA”. This part is likely a single to double-ended converter, as the input is definitely single ended, and the ouput appears differential (given two 47 ohm resistors).

Following this part is an AD8330, which is a DC to 150 MHz VGA. This part has enormous gain range, and it likely where the scope forms its attenuator/gain for the various Y-scale sensitivity settings. The gain on this part is controlled via DC voltages.

And finally we get to what is the ADC. This is likely a 100Msps, 10-bit part given the scope specs. A quick search on Google brings up a MAX 19516 as one candidate, but I haven’t traced the pins to see if this is correct or not.

That’s about it for now.



  1. The ADC can’t be the MAX 19516 because it only comes in a leadless paskage.

    Comment by jb — November 17, 2011 @ 12:20 am

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