Re: Ugly xfer function - repost from seb

From: Jim Thompson (thegreatone_at_example.com)
Date: 08/09/04 

Date: Sun, 08 Aug 2004 17:55:02 -0700

On Sun, 8 Aug 2004 20:36:36 -0400, Active8 <reply2group@ndbbm.net>
wrote:

>On Sun, 08 Aug 2004 16:33:09 -0700, Jim Thompson wrote:
>
>> On Sun, 8 Aug 2004 00:21:13 -0400, Active8 <reply2group@ndbbm.net>
>> wrote:
>>
>>>Originally posted in seb, but Ban doesn't think it belongs there :)
>>>
>>>Being a true masochist, I thought I'd try deriving the Laplace xfer
>>>function for this filter and it's getting ugly. Before I go further,
>>>I thought I'd ask if I'm setting it up right, er, umm, ...
>>>efficiently?
>>>
>>>
>>> +------+-------+ _______
>>> | | | 1 | R1+R3
>>> | .-. | fr= ----- \|-------
>>> --- | |R2 | 2pi*C R1*R2*R3
>>> C1 --- | | |
>>> | '-' | R2
>>> ___ Vx | || | |\ | gain= - -----
>>>Vi o-|___|-+--+--||--+--|-\ | 2R1
>>> R1 | || | >-+-o Vo
>>> .-. C2 +--|+/
>>> | |<-+ | |/
>>> R3| | | | 1
>>> '-' | | Bandwidth= -------
>>> | | | pi*R2*C
>>> === === ===
>>> GND GND GND
>>>
>>>created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de
>> [snip]
>>
>> Why would anyone want to use such a gross Sallen-Key-like
>> configuration (other than being penny-ante and only use one OpAmp)?
>>
>> The Gyrator configurations shown on the S.E.D/Schematics page of my
>> website use two OpAmps, but give independent control of Q and center
>> frequency.
>>
>> ...Jim Thompson
>
>This is just an excersize for me, Jim. I have few practical problems
>to play with to improve my analysis skills, but since you offered,
>I'll be doing your gyrator next. BTW, your Sedra Espinoza inspired
>me to look at nets like this and Ban just happened to throw someone
>this bone without the full derivation, so I jumped on it. Timely,
>no?

Yep! Every EE should have loop and nodal analysis mastered.

                                        ...Jim Thompson 

-- 
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.