Hi, I have a question about using AD8561 for 100kHz or higher frequency Sine to Square Wave Conversion.
The comparator I'm using is AD8561 and the circuit diagram I set up on breadboard is
And the response I get is as follows, with sine wave as input and blue as pin7 output.
Is there a way to get rid of these ripple/oscillation and get 7ns response bandwidth?
The images did not come through. When I try to look at them, it takes me to gmail.
Can you attach PDF files or jpeg? You can generate a PDF file with www.cutepdf.com
It will look like a printer that you print to, but it will give you a PDF file.
As a side note, with very fast parts, you need a clean pc board layout, adequate bypass caps, etc.
and a little bit of positive hysteresis as described in the apps section of the data sheet.
Thank you Harry for your reply. I apologize that the pictures didn't show up. I attached the pictures again here.
I did bypass the supplies.
Take a look at figs 5 and 6 in MT-083. You need hysteresis. Try 10 ohm in, 1k feedback. If that
doesn't work, change to 20/1k
Hi, Harry, I got weird looking signals.
I tried out using 10 or 20ohm resistors.
The diagram of the circuit I test is
The response is:
One can see that even the input signal is distorted at the zero crossing.
Also I don't understand why the logic "0" looks so weird below 0V.
It's a little hard to read the graphs, but if the purple trace is about 0.7V below the input, I would suspect your -5V is really zero, or not very stiff. Measure directly at the part for +5, -5, and ground. (which package?)
It looks like you are running on +5V and ground. Also look at pin 8; it should be an inverted pin 7.
What is your source? Source impedence??
Also try a sine wave with +/-0.5V. Looks like you are running +2.5V to -2.5V which should work, but
drop the amplitude and see what happens.
Are you using one of those white breadboarding strips? or a pc board?