Diamond buffer

[peranders]

Jan, just compare my buffer with the one Walter Jung has drawn and to a regular one, BUF634 for instance. The difference is cascodes, transistors which only act as diodes and R14 and R15. Why have I done this? Only to limit the amount of different parts. How would you done a diamond buffer?

The pullup, pulldown resistors is just in case only. You can use this buffer with single supply.

All measurements is without feedback, just the buffer alone. I have though a reservation about the measurements but Walt Jung claimed rather good performance and when was he totally wrong?

SMD is "ont i stjärten"(*) when it comes to repair but don't break it.... just design in protection which works if it is needed. In my case I have no protection because it should work in known conditions. Walter Jung had suggestions how it could be done.

The loads I have used are 100k, 220 ohms and 55 ohms.

(*) Fred will translate for you...

[peranders]

Originally posted by PMA
Per,

I did not know you were interested in Gainclone clones development and sale ....

I felt like it but it's not the Fred style exactly. It's super universal, inverting och non-inverting buffer, inverting or non-inverting LM3886, DC-servo or not for both inverting and non-inverting LM3386, bridge connection in inverting or non-inverting mode with non-inverting or inverting input buffer with or without input coupling caps along with an optional output filter plus an input filter....have I forgot something?... it's not SMD : :up

[costiss]

how much are the pcbs cost? in your site stated is : ???
btw, amazing construction quality..

[peranders]

I have not desided this yet. Check back in a couple of days. How much do you want to pay?

[capslock]

What is the Walt Jung article you are referring to, Per? Is it available on the web?

Regards,

Eric

[peranders]

http://www.elecdesign.com/Globals/Pl...tent/2800.html

The rest is gone for the moment, can't be found. Maybe they will turn up some day.

Scanned articles at Walt's homepage.
http://home.comcast.net/~walt-jung/wsb

[peranders]

I have done a simulation of this diamond buffer and I get a bandwidth of around 300 MHz. The BC860, 850 were changed to 2N3904 and 2N2907 but the output transistors were the right ones, BCP53 and BCP56.

Is a bandwidth clearly over 100 MHz possible?

[sonnya]

NO!, are you sure about this sim. Try with another spicemodel.

If i remember right i have gotten something like 10 - 20MHz.

[peranders]

I have now tested with BC860/850 and the result is 200 MHz.

[sonnya]

Hi Per.

Yes you are right about the wide bandwidth ...

I got 260MHz with a source impedance of 1 Ohm.
I got 123MHz with a source impedance of 100 Ohm.
And i got 35MHz with a source impedance of 1 KOhm.

But i would say that in a real world application The buffer will run around 1KOhm - 20Ohm at > 20MHz.

A fast opamp like the AD8610 will have a Zout peaking at 60MHz of 50Ohm.