[sdiy] improved dynamic range diffpair-vca

[harrybissell at copper.net]

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
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