Path: utzoo!utgpu!attcan!uunet!husc6!purdue!iuvax!silver!commgrp
From: commgrp@silver.bacs.indiana.edu
Newsgroups: sci.electronics
Subject: Re: Log amps, sqare root amps
Message-ID: <7200016@silver>
Date: 17 Oct 88 17:09:00 GMT
References: <913@cseg.uucp>
Organization: Indiana University CSCI, Bloomington
Lines: 27
Nf-ID: #R:cseg.uucp:-91300:silver:7200016:000:808
Nf-From: silver.bacs.indiana.edu!commgrp    Oct 17 12:09:00 1988




>I am currently working on a video project, and I need a 
>logarythmic amplifier or a square root amplifier. The catch is 
>that I need it to run at 5-10 MHZ.  Analog devices has one they 
>specify to work at 10 MHZ to 250 MHZ, but I am  not sure it is 
>perfect for the job. Any body out there know of any others that I 
>could use?
>
>  Greg Garner
>  gmg@hcx.uucp
>  501-442-4847

I don't know where to get the device you need, but here's 
a precaution when using log and other nonlinear amps:

The amplifier's gain-bandwidth product is constant, the gain 
varies depending upon input signal level, therefore the bandwidth 
varies in inverse proportion.  Inspect manufacturers' data sheets 
cary carefully; their bandwith specification is probably at unity 
gain.

--

Frank
reid@gold.bacs.indiana.edu