OPA549 Gainclone Layout

n00beR · 15th January 2005, 05:08 AM

Hi All,

I have been regitered here for a while now, but haven't made any contributions

I was wondering if you guys would be so kind as to have a look at my OPA549 Gainclone design.
My design is just "copies" of others I have seen, and jumbled around a bit to make it my own

I'm new to circuit design so all comments, tips and suggetions are welcome.

I will post the eagle file incase anyone wants a closer look.

But for now here is a screen shot:

n00beR · 15th January 2005, 08:30 AM

... and here is the eagle file:

Alcaid · 15th January 2005, 10:23 AM

There is no connection between signal ground and power ground.

Alcaid · 15th January 2005, 10:25 AM

also the gain is too high for the OPA549.
You have a voltage gain of (22/1+1=) 23.
Try something like 11. (1k and 10k resistors.)

Alcaid · 15th January 2005, 11:03 AM

The output trace from pin 1,2 is too thin. The OPA549 can deliever 8A continuous.

n00beR · 15th January 2005, 11:11 AM

I have applied your suggestions Alcaid, nd have attached the new image below.

Would this implementation suffice?

Alcaid · 15th January 2005, 11:18 AM

These chips need a low gain because of their low GBP, but remember that with a gain of 11 you need some more gain in another stage like an active preamplifier (or just an opamp circuit in the amp). I use a voltage gain of 3 in my DIY preamp, and 3 x 11 = 33 which would be sufficient.

Alcaid · 15th January 2005, 11:25 AM

Instead of using a jumper, you could connect SG-PG like this:
(The PCB will be a little bigger though)

Alcaid · 15th January 2005, 11:32 AM

+ a little Eagle tips:
Try to use a standard grid of something like 50 mils or 25 mils (grid set to inch) instead of 0.0001mm or what you were using. With that grid it is almost impossible to put the components/traces where you want them.

n00beR · 15th January 2005, 11:44 AM

Quote:

Originally posted by Alcaid
Instead of using a jumper, you could connect SG-PG like this:
(The PCB will be a little bigger though)

LOL you beat me too it alcaid that was my next question, or could i join pins 3, 6 and 8 as they all connect to ground? or does this cause other problems?

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15th January 2005, 10:23 AM	#3
Alcaid diyAudio Member Join Date: Nov 2003 Location: Klepp	There is no connection between signal ground and power ground.

15th January 2005, 10:25 AM	#4
Alcaid diyAudio Member Join Date: Nov 2003 Location: Klepp	also the gain is too high for the OPA549. You have a voltage gain of (22/1+1=) 23. Try something like 11. (1k and 10k resistors.)

15th January 2005, 11:03 AM	#5
Alcaid diyAudio Member Join Date: Nov 2003 Location: Klepp	The output trace from pin 1,2 is too thin. The OPA549 can deliever 8A continuous.

15th January 2005, 11:18 AM	#7
Alcaid diyAudio Member Join Date: Nov 2003 Location: Klepp	These chips need a low gain because of their low GBP, but remember that with a gain of 11 you need some more gain in another stage like an active preamplifier (or just an opamp circuit in the amp). I use a voltage gain of 3 in my DIY preamp, and 3 x 11 = 33 which would be sufficient.

15th January 2005, 11:32 AM	#9
Alcaid diyAudio Member Join Date: Nov 2003 Location: Klepp	+ a little Eagle tips: Try to use a standard grid of something like 50 mils or 25 mils (grid set to inch) instead of 0.0001mm or what you were using. With that grid it is almost impossible to put the components/traces where you want them.

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