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Maybe if you use correct terms people will understand you. what do you mean by hole, there are many types of holes(via is also a hole), be more specific. Do you mean "polygon cut out"? So far you have been useless, maybe you should just not write here.
You are a lifesaver d123 :D . I connected the probe as shown in the figure and I was able to see it. However, there was a noise. I tried using a similar probe to connect the non-inverting input of the OPAMP and the noise is very low. So the whole problem was about connecting the probe properly...
1594624845
Coupling-AC (tried also DC but doesn't change)
BW limit-OFF
Invert-OFF
Probe-1.00:1
Skew-0.0s
Units-Volts
1594625495
Yes, I tried removing negative, positive, and both.
I noticed that before I connect the probe to the output, and measure the ground, there is an oscillation at (1kHz from the signal generator to non-inv input of opamp) at around 1kHz(very noisy). when I connect the probe to the output of the opamp and probe the ground there is 20MHz oscillation...
Thank you, I will move de-coupling cap closer to the pins and add vias close to their ground connection and share the last version. I hope this time caps are close enough.
1594361415
Thank you, I made them closer and put vias near caps and R1 ground connection. Put jumper wire across the...
I actually removed the OPA657 and testing OPA847 only with signal generator inputting from non-inverting input of opamp and measuring after 50R with an oscilloscope. As you said I tried different combinations of capacitors as the bypass but it, unfortunately, didn't help. Maybe the problem is in...
Thanks for the feedback Dana, I posted on the TI forum https://e2e.ti.com/support/amplifiers/f/14/p/916824/3398364#3398364 but was not able to solve my problem. Many people have this problem, the majority solved their high-frequency issue by:
1. Putting 50R at the output pins and measuring after...
No, but they wouldn't sell unless it's operational? I am trying to solve my problem. Your advice and help are highly appreciated and but I don't want to have an argument with you.
In the link I sent, there is a well-functioning amplifier with OPA847. I tried to make it similar to that.
https://www.aliexpress.com/item/33011696079.html
Hi, I tried to follow this design. He also removed the ground polygon pour under the ICs. https://www.aliexpress.com/item/33011696079.html
I thought caps are close enough to the positive power. Should I make it even more closer?
There is 0.1uF 0603 ceramic, 0.1uF tantalum, and 10uF alum electrolytic cap. on positive and negative supplies. Additionally, there is also a ferrite bead. BLM21BD272SH1.
1594209068
Thanks, Dana, I exercised with 100R and directly with hands. There is a very small freq change, almost not...
Hi Dana, I will use .01 and .1 in parallel next time, keeping in mind the ERS values from Datasheet and making sure they are suitable to be used as bypass capacitors.
As you said I loaded nodes with C using 1kR and hand. The 20MHz decreased to 19.8MHz. What should I conclude from this...
Hi, as in the picture, I tried to put bypass capacitors as close as possible to the power pins of the opamp(I replaced 1206 tantalum capacitors with 10uF alum electrolytic cap). There are electrical connections between the top and bottom polygon pour (shown with yellow, they are connected in...
Hi, Dana. I am measuring after the 50R and before the BNC jack(I removed BNC, there is just a test point). When I use 1X there is 20MHz oscillation and when 10X used, its 26MHz. And when I use BNC to crocodile connector there is 12MHz oscillation.
I was not able to understand,
What node is...
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