Re: Op-amp circuit....

From: Tim Wescott (tim_at_wescottnospamdesign.com)
Date: 01/09/05 

Date: Sun, 09 Jan 2005 14:02:15 -0800

Jim Thompson wrote:

> On Sun, 09 Jan 2005 11:28:41 +0100, Andy <andy@nodomain.nod> wrote:
>
>
>>FrozenOne wrote:
>>
>>>Okay so to answer some of the questions:
>>>
>>>1) The voltage has to be continuous between the points; I am not just
>>>looking for those points
>>>2) Precision has to be close, but not exact
>>>3) Do not want to implement digital method
>>>4) I am making the circuit to control the response of an RF attenuator
>>>that I am using to improve on an older system, and as you can see
>>>Analog stuff is not my strong point. The Existing system can change
>>>the output by 6dB by varying the control from 11.7-12.5 volts. These
>>>numbers cannot change. I am attempting to implement a COTS attenuator
>>>to do the same function, but I need to map the existing control voltage
>>>to the COTS attenuator voltages. I hope this makes sense.
>>>
>>>I am thinking the PWL approach might be a good way to solve my problem
>>>
>>
>>The slope looks increasing. If you have only 3 reference points, maybe a
>>an exponential amplifier could suffice?
>>
>>(Cf. http://www.national.com/an/AN/AN-311.pdf , figure 2.)

Read back. The Frozen One seems to have settled on PWL (which is the
right way to go if it's good enough), but everyone felt the need to
expand on my quadratic/processor suggestion.

Go figure. 

-- 
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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