Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.electronics.design > #469247 > unrolled thread

Diode Array

Back to article view | Back to sci.electronics.design

Contents

  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

#469247 — Diode Array

I'm looking for a replacement for the  CA3039 diode array, which has been successfully used in a precision demodulator circuit operating up to 1 MHz. The part has been obsoleted by Intersil.  The important characteristics are low leakage current (less than 0.1 nA at 25C with 1 V reverse bias) and close matching of forward voltage drops. Also, the forward voltage drop with 1 nA or less current needs to be 200 mV or greater.  Most common diodes turn on much earlier. The operating range is from 20C to 60C.  
Thank you for your help.

[toc] | [next] | [standalone]

#469288

On 7/18/2017 8:29 AM, xmacleod@gmail.com wrote:
> I'm looking for a replacement for the  CA3039 diode array, which has
> been successfully used in a precision demodulator circuit operating
> up to 1 MHz. The part has been obsoleted by Intersil.  The important
> characteristics are low leakage current (less than 0.1 nA at 25C with
> 1 V reverse bias) and close matching of forward voltage drops. Also,
> the forward voltage drop with 1 nA or less current needs to be 200 mV
> or greater.  Most common diodes turn on much earlier. The operating
> range is from 20C to 60C. Thank you for your help.
> 

You must have measured the above parameters yourself. The datasheet does 
not even get close to your requirements. How do you expect people to 
help you? I don't think anyone will purchase a bunch of diodes and 
parametertize them for you.

[toc] | [prev] | [next] | [standalone]

#469295

On Tuesday, July 18, 2017 at 9:29:21 AM UTC-4, xmac...@gmail.com wrote:
> I'm looking for a replacement for the  CA3039 diode array, which has been successfully used in a precision demodulator circuit operating up to 1 MHz. The part has been obsoleted by Intersil.  The important characteristics are low leakage current (less than 0.1 nA at 25C with 1 V reverse bias) and close matching of forward voltage drops. Also, the forward voltage drop with 1 nA or less current needs to be 200 mV or greater.  Most common diodes turn on much earlier. The operating range is from 20C to 60C.  
> Thank you for your help.

How about a quad transistor array?  Use the BE or BC diode... 
I see matched ones at Digikey, but spendy.  

George H.

[toc] | [prev] | [next] | [standalone]

#469304

On Tue, 18 Jul 2017 06:29:14 -0700 (PDT), xmacleod@gmail.com wrote:

>I'm looking for a replacement for the  CA3039 diode array, which has been successfully used in a precision demodulator circuit operating up to 1 MHz. The part has been obsoleted by Intersil.  The important characteristics are low leakage current (less than 0.1 nA at 25C with 1 V reverse bias) and close matching of forward voltage drops. Also, the forward voltage drop with 1 nA or less current needs to be 200 mV or greater.  Most common diodes turn on much earlier. The operating range is from 20C to 60C.  
>Thank you for your help.

Have you considered buying the real part from a surplus parts dealer?
You probably won't like their prices, but it will be less than the
cost of redesigning the device, approving a new vendor, inspecting
parts, etc.

<http://www.integrated-circuit.com/products-detail/CA3039/EIS-398091.html>
<http://www.key-chips.com/products-detail/4307116/CA3039.html>
<http://www.4starelectronics.com/part_detail/CA3039.html>
etc...

-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

[toc] | [prev] | [next] | [standalone]

#469333

>I'm looking for a replacement for the  CA3039 diode array, 
>which has been successfully used in a precision 
>demodulator circuit operating up to 1 MHz. The part has been 
>obsoleted by Intersil.  The important characteristics 
>are low leakage current (less than 0.1 nA at 25C with 1 V 
>reverse bias) and close matching of forward voltage drops. 
>Also, the forward voltage drop with 1 nA or less current 
>needs to be 200 mV or greater.  Most common diodes turn 
>on much earlier. The operating range is from 20C to 60C.   

It's probably time to replace the old-school method with a nice fast CMOS mux. You can get the desired dead zone by controlling the duty cycle. A simple method is to use a 74HC4017 1-of-10 decade counter: OR together outputs 1-4 for one switch phase, and 6-9 for the other. You'll get a one-clock deadband at the switching points. 

Cheers

Phil "also from the old school" Hobbs

[toc] | [prev] | [next] | [standalone]

#469514

On Tuesday, July 18, 2017 at 6:29:21 AM UTC-7, xmac...@gmail.com wrote:
> I'm looking for a replacement for the  CA3039 diode array, which has been successfully used in a precision demodulator circuit operating up to 1 MHz. The part has been obsoleted by Intersil.  The important characteristics are low leakage current (less than 0.1 nA at 25C with 1 V reverse bias) and close matching of forward voltage drops. Also, the forward voltage drop with 1 nA or less current needs to be 200 mV or greater.  Most common diodes turn on much earlier. The operating range is from 20C to 60C.  

Presumably you like matching for the same reason RF duals for PIN switches or protection are  matched.
Would a trio of matched duals do as well as a set of six?

<http://www.skyworksinc.com/uploads/documents/SMP1330_Series_200050N.pdf>

The usual diode arrays are, nowadays, not tested for any kind of matching.  If you want enough,
though, a manufacturer can test for any criteria you care to specify.   The specs above are NOT
what a CA3039 datasheet shows, but can be inferred from other data in the sheet.

[toc] | [prev] | [next] | [standalone]

#469555

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.
Thanks       

[toc] | [prev] | [next] | [standalone]

#469558

On Wednesday, July 19, 2017 at 9:05:34 AM UTC-4, xmac...@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.
> Thanks

I made (and sell) a 'silly' audio mixer that is an audio transformer 
and diode ring.  I found that I got better performance out of 
diode connected transistors than from other diodes I tried.  

George H.

[toc] | [prev] | [next] | [standalone]

#469593

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.


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#469606

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

[toc] | [prev] | [standalone]

Back to top | Article view | sci.electronics.design

csiph-web