Circuit topology looks similar to this amp:
stereoplay 1988 Monoblock from Günter Mania
for schematic go to post #4 under
http://www.diyaudio.com/forums/solid-state/190380-burmester-avm-schematics.html#post2598494
Wow, thanks for the lead. That's very interesting, the complementary pair of transconductance input error stages, each using a complementary pair of BJTs, and the folded-cascode VAS stage, is the same as in my amplifier. The devices and operating currents are of course quite different.
As I mentioned, I got the idea from the 50-ohm output amplifier in the Tektronics PG508 50MHz pulse generator. It uses the same input-stage circuit. This circuit has the advantage of being very fast, because it can run at high currents and doesn't require mirrors or high-gain common-emitter stages. It doesn't have very high open-loop gain, and the folded cascode stage, with pullup resistors instead of current sources, has some intrinsic distortion. So even though it has a blisteringly-fast slew rate, an audiophile would find things to criticize. But it makes an amazing DC-10MHz lab power amplifier. Several are in use now, generating quadrature electric fields for electro-rotation experiments, running at several hundred volts (with the help of a transformer) at 2.5MHz.
My earliest copy of the PG508 manual is dated Nov, 1975. My schematic copies are rev B, dated 1980. I have a 1986 catalog with a PG507 and PG508 datasheet page. Yessir, those Tektronix engineers were pretty advanced for their time!
As I mentioned, I got the idea from the 50-ohm output amplifier in the Tektronics PG508 50MHz pulse generator. It uses the same input-stage circuit. This circuit has the advantage of being very fast, because it can run at high currents and doesn't require mirrors or high-gain common-emitter stages. It doesn't have very high open-loop gain, and the folded cascode stage, with pullup resistors instead of current sources, has some intrinsic distortion. So even though it has a blisteringly-fast slew rate, an audiophile would find things to criticize. But it makes an amazing DC-10MHz lab power amplifier. Several are in use now, generating quadrature electric fields for electro-rotation experiments, running at several hundred volts (with the help of a transformer) at 2.5MHz.
My earliest copy of the PG508 manual is dated Nov, 1975. My schematic copies are rev B, dated 1980. I have a 1986 catalog with a PG507 and PG508 datasheet page. Yessir, those Tektronix engineers were pretty advanced for their time!
You can always attach new ones
e.g. The thread owner can always update the first message of the thread.
Thanks again for sharing this amplifier, it's just about perfect for our application and doesn't require me reinventing the wheel.
We've got a nice Krohn-Hite lab amp at work, which is probably a bit overbuilt for what we do, but I remembered you posted this a while ago and happy I found it, as it looks like we need a couple more high bandwidth amps for some dielectrophoretic experiments that run from audio through a couple MHz. Will probably scale back a bit on the output devices, as I think the hardest load is closer to 250-300 ohms. Fortunately we have a bunch of 33120's laying around so I just need a buffer/amp.I have the original copy of AoE on my bookshelf, which I bought in high school. Probably time to get the update!
EDIT: PCB gerbers are in the dropbox link at the very end of the first post.
Samuel Groner has also found use for this kind of topology:
https://www.eetimes.com/document.asp?doc_id=1279853&page_number=4
Samuel Groner has also found use for this kind of topology:
https://www.eetimes.com/document.asp?doc_id=1279853&page_number=4
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Thanks Anthony. My board house import complains there is no drill file in the Gerber set. Although there is a file with the .DRL suffix.
Layers seem to import and display fine.
Anyone know what Gerber format this is? RX274? Extended?
Jan
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