[sdiy] improved dynamic range diffpair-vca

[harrybissell at copper.net]

That's the one. Dolby is making an HPF
anyway.  You could do a Moog HPF with this
architecture... but you'd need a LOT of transistors
for a four pole implementation. OTOH it might be able
to hangle quite a large signal that way.

(otoh the HPF is a little boring imho :^)

H^) harry

>
>
>
>---- Original Message ----
>From: houshu at muj.biglobe.ne.jp
>To: harrybissell at copper.net
>Subject: Re: [sdiy] improved dynamic range diffpair-vca
>Date: Fri, 27 Apr 2007 02:21:43 +0900 (JST)
>
>>Hello Harry,
>>
>>This one?
>>
>>http://www.pat2pdf.org/patents/pat3761741.pdf
>>
>>Sam Hoshuyama
>>
>>From: harrybissell at copper.net
>>Date: 2007/04/27 00:23:05
>>> Checking out the patent (Dolby) and the patents referenced 
>>> in that patent... it looks a lot like the Moog HPF architecture
>>> with added transistors for higher linearity....
>>> 
>>> They did disclose that 'one' transistor would work...
>>> 
>>> The main benefit (imho) from the bipolar method is you do not
>>> need a FET. That would be a big benefit to someone with a
>>> monolythic process like Signetics.  Don't need to fabricate
>>> FETs on the chip.
>>> 
>>> It would be a pain to do discretely, imho
>>> 
>>> H^) harry
>>> 
>>> 
>>> 
>>> >>pair with a lot of diodes at the common emitter (Fig. 6).
>>> >>
>>> >>  http://www.pat2pdf.org/patents/pat4068139.pdf
>>> >>
>>> >>  An OTA with 100% feedback works as a variable resistor.
>>> >>
>>> >>It was published in 70's.  So, the Japanese patent application 
>>> >>can not be patented  ;-)
>>> >>
>>> >>Sam Hoshuyama
>>> >>Saitama, JAPAN
>>> >>
>>> >>
>>> >>From: Aaron Lanterman <lanterma at ece.gatech.edu>
>>> >>Date: 2007/04/26 03:28:30
>>> >>> 
>>> >>> On Thu, 26 Apr 2007, HOSHUYAMA wrote:
>>> >>> 
>>> >>> > Actually, what I saw the circuit topology was a patent
>>> >application (In 
>>> >>> > Japan, almost all the patent applications becomes public
>after
>>> >one and a 
>>> >>> > half years.) not a filed patent.
>>> >>> >
>>> >>> > A couple of years ago, I saw the same structure in a
>Japanese 
>>> >>> > electronics book published in 80's. I guess, the structure
>was
>>> >not 
>>> >>> > patented.
>>> >>> 
>>> >>> Interesting! Thanks!
>>> >>> 
>>> >>> - Aaron
>>> >>> 
>>> >>>
>>>
>>--------------------------------------------------------------------
>-
>>> >--------
>>> >>> 
>>> >>> Dr. Aaron Lanterman, Asst. Prof.
>>> >>> and Demetrius T. Paris Junior Prof.  Voice:  404-385-2548
>>> >>> College of Electri. and Comp. Eng.   Fax:    404-894-8363
>>> >>> Georgia Institute of Technology      E-mail:
>>> >lanterma at ece.gatech.edu
>>> >>> Mail Code 0250                       Web:   
>>> >users.ece.gatech.edu/~lanterma
>>> >>> Atlanta, GA 30332                    Office: Centergy 5212
>>> >>> 
>>> >>> 
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>>>