Analog computing question - how to implement X^Y=Z - diyAudio
Go Back   Home > Forums > General Interest > Everything Else
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 24th March 2010, 10:48 PM   #1
diyAudio Member
Join Date: Sep 2005
Default Analog computing question - how to implement X^Y=Z

An attempt at a thought provoking question for the analog computing types:

In the world of analog circuits, how would one implement the function

X ^ Y = Vout?

That is, a circuit block with two inputs, X and Y (inputs can be voltage or current). The output voltage (or current) is equal to the input X, raised to the power of Y (Y is also an input).

One way I can think of doing it is:

X ^ Y = exp(y * ln(x))

This uses a logarithmic amplifier, exponential amplifier, and one multiplier. Are there other ways/circuits to implement this function?
  Reply With Quote
Old 24th March 2010, 11:04 PM   #2
diyAudio Member
zigzagflux's Avatar
Join Date: Oct 2006
Location: Charlotte, NC
They do make analog multipliers in integrated circuit form. On Semi used to, at least.
  Reply With Quote
Old 25th March 2010, 12:08 AM   #3
jcx is online now jcx  United States
diyAudio Member
Join Date: Feb 2003
Location: ..
Analog Devices is a big player in analog function blocks:
Analog Multipliers/Dividers | Other Products | Analog Devices
also look for log amps

but today single chip flash uC with ADC and DAC can give good results for applcations that fit the resolution and speed of the digital implementation

Last edited by jcx; 25th March 2010 at 12:12 AM.
  Reply With Quote
Old 25th March 2010, 12:43 AM   #4
diyAudio Member
Join Date: Jan 2008
Location: Virginia
One log amp for the X signal (X needs to be positive).
The result feed into a multiplier with Y.
The third result fed to a good OpAmp that has in the feedback network another log amplifier (to result the exp function).
  Reply With Quote


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
nVidia CUDA GPU computing PC FIR KOON3876 Digital Line Level 68 4th December 2013 07:28 AM
How can I implement the D1-Stage with an Ultra-Analog-DAC (parasound 2000)? Blitz Pass Labs 31 6th August 2013 08:53 PM
tube basics: computing mu and transconductance jarthel Tubes / Valves 11 31st January 2012 11:15 PM
Computing or measuring anode curves w/ CFB Tubes4e4 Tubes / Valves 3 19th May 2009 10:31 PM
Computing question: VPNs trwh Everything Else 2 1st November 2004 11:25 PM

New To Site? Need Help?

All times are GMT. The time now is 11:21 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2