Log Amp

Tim... take a look at this one.

Similar design was for the big weather guys.

Maybe it is what you are looking for.

Yes, it is elaborate... not just diodish'. ;-)

If it is too much for the whole job, you should at least make one.

That IS a NICE document!

Yeah, it seems they did a bit of creativity (perhaps the process offers two types of resistors that have different tempcos) there in the black box. =20 Their claims are good, though they aren't tested parameters according to the "note 4". =20

Bob Pease was working on an update to it, the day he died.

"Recently Bob was working on material for National.com called "How to Choose an Op Amp" featuring sage advice and his inimitable style. He was also updating the popular application note, AN-31, a collection of op amp circuits dating back 1969. He was in the process of writing about the history and evolution of these circuits and the best ways to implement these circuits using today's op amps."

Did you look at the circuit I posted for you?

Meant to add. That I found a Philbrick appnote on Log Amps.

Pease be with you

There is also some good (better IMO) info on log amps in the long out of print Analog Devices Nonlinear Circuits Handbook. While Analog Devices did not take my suggestion that they make it available on their web site, a google search will turn up a number of places to download it free. Combine this with Bob Pease's article on how to make a single stage log amp fast and stable at the same time (as opposed to the even faster log- strip multi-stage approach) and you have something.

Pease and Philly Cheese (bricks)? :-)

My log amp works.

For photodiode current measurement I've used the AD8304.

This is a realy simple way to get repeatable wide dynamic range power meters.

cheers

David

That could be an avionics mode-S transponder.

:-) Gerhard

IMHO also radar IF..?

Jorgen