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Re: Diode Array

From	Tauno Voipio <tauno.voipio@notused.fi.invalid>
Newsgroups	sci.electronics.design
Subject	Re: Diode Array
Date	2017-07-19 21:12 +0300
Organization	A noiseless patient Spider
Message-ID	<oko776$5jd$1@dont-email.me> (permalink)
References	<eb0d9703-8f2f-46f0-9e9e-1b833d4bb5bc@googlegroups.com> <05077c77-776c-4a65-961f-6bf8fdb16af8@googlegroups.com> <ccf974ff-c85c-47f7-87bf-7f5dd95f3566@googlegroups.com> <oko03402t64@drn.newsguy.com>

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On 19.7.17 19:07, Winfield Hill wrote:
> xmacleod@gmail.com wrote...
>>
>> Thank you for the comments and suggestions.  I made some
>> measurements of a diode connected transistor, 2N3904 BC
>> shorted, and it provides the low leakage and forward
>> voltage characteristics needed. Interestingly, the forward
>> voltage characteristics are more like the CA3039 than a
>> switching diode.  For instance, the forward voltage at
>> 0.1 uA is about 400 mV, whereas for a 1N4148 diode, it
>> is about 150 mV. Also, the CA3039 diode array has a typical
>> reverse breakdown of 5 V, similar to a transistor BE junction.
>> Is the CA3039 actually an array of diode connected transistors?
>> I will look further in to using matched transistor arrays.
>> Any recommendations for devices are welcome.
> 
>   The high voltage you refer to means the current density
>   is higher, which means the part is smaller.  Small dies
>   also have lower capacitance.  I suppose that's actually
>   the parameter you're concerned with?  Working at high
>   wold normally imply approaching distortion.


My guess is that the OP is using a ring mixer. Its output
level is limited by the forward drop of the diodes. It seems
thet this was the reason the first ring mixers (modulators)
in telephony carrier system were made with several diodes
in series in each branch.

-- 

-TV

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Thread

Diode Array xmacleod@gmail.com - 2017-07-18 06:29 -0700
  Re: Diode Array John S <Sophi.2@invalid.org> - 2017-07-18 11:24 -0500
  Re: Diode Array George Herold <gherold@teachspin.com> - 2017-07-18 09:45 -0700
  Re: Diode Array Jeff Liebermann <jeffl@cruzio.com> - 2017-07-18 10:01 -0700
  Diode Array pcdhobbs@gmail.com - 2017-07-18 11:17 -0700
  Re: Diode Array whit3rd <whit3rd@gmail.com> - 2017-07-18 22:20 -0700
    Re: Diode Array xmacleod@gmail.com - 2017-07-19 06:05 -0700
      Re: Diode Array George Herold <gherold@teachspin.com> - 2017-07-19 06:22 -0700
      Re: Diode Array Winfield Hill <hill@rowland.harvard.edu> - 2017-07-19 09:07 -0700
        Re: Diode Array Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-07-19 21:12 +0300

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