On a design I am working right now I need to drive differential cables at up to 100MHz and with gusto, several volts swing. I'd use coax instead but the customer is king. Looking at the various diff amps du jour I consistently find specs like this: That example has all the performance data at an even higher load resistance of 800ohms. Considering that regular ribbon is around 100ohms diff and even grandpa's old TV cable was 300ohms, what good does that do? I guess now I have to not just find a diff amp but also add an analog diff buffer IC (if they still exist) or roll my own transistor stuff. Which will double as a space heater where I really can't use heat. Grumble! -- Regards, Joerg

That's a lot of spec sheet.. I didn't read it all. Max current >100mA that should be enough current for ~100 ohms. Maybe some spec is better when driving 800 ohms. (less distortion? see figure 69.) George H.

Den torsdag den 28. december 2017 kl. 01.17.34 UTC+1 skrev Joerg: would this do?

Diff amps spec at 500ohms plus, why?

Dec 21, 2017 42 Replies

Rate this thread:

Lasse Langwadt Christensen 8 years ago

would this do?

formatting link

Vote

Joerg 8 years ago

It has the same problem as the others. Inputs spec for 100ohms which is customary for diff lines such as ribbon. Output spec for 200ohms which is nonsensical in this day and age. Who writes datasheets these days? college kids? Marketing droids?

Regards, Joerg http://www.analogconsultants.com/

Vote

Joerg 8 years ago

The ones I have seen use discretes in the final stage.

[...]

Regards, Joerg http://www.analogconsultants.com/

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required