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BJTs as ultra low leakage protection diodes

Started by Ebrahim ●June 12, 2009
Hello, I want is there anyone that has used a BJT instead of ultra low 
leakage diode(<10pA) in a serious design. The reason that I do not use 
JFET is that I need high breakdown(100V) voltage. So I also need 
Bootstrapping  I have down some measurements with different JFETs and 
BJTs and I didn't find quite big differences.
Reply by Ebrahim ●June 12, 20092009-06-12
Ebrahim wrote:
Sorry I forgot to say that I mean Collector-Base Diode of BJT.

Regards
Reply by Robert Baer ●June 12, 20092009-06-12
Ebrahim wrote:

> Hello, I want is there anyone that has used a BJT instead of ultra low 
> leakage diode(<10pA) in a serious design. The reason that I do not use 
> JFET is that I need high breakdown(100V) voltage. So I also need 
> Bootstrapping  I have down some measurements with different JFETs and 
> BJTs and I didn't find quite big differences.

   Do not think BJTs in general are that good; try an LED...
Reply by Phil Allison ●June 12, 20092009-06-12
 Ebrahim wrote:



>> Hello, I want is there anyone that has used a BJT instead of ultra low 
>> leakage diode(<10pA) in a serious design.


"Ebrahim"

** You are a totally stupid pile of autistic shit, a waste of space a waster
of good people's valuable time.

    Fuck off and DROP DEAD  !!!













 The reason that I do not use

>> JFET is that I need high breakdown(100V) voltage. So I also need 
>> Bootstrapping  I have down some measurements with different JFETs and 
>> BJTs and I didn't find quite big differences.
>   Do not think BJTs in general are that good; try an LED...
Reply by Ebrahim ●June 13, 20092009-06-13
Robert Baer wrote:

> Ebrahim wrote:
>> Hello, I want is there anyone that has used a BJT instead of ultra low 
>> leakage diode(<10pA) in a serious design. The reason that I do not use 
>> JFET is that I need high breakdown(100V) voltage. So I also need 
>> Bootstrapping  I have down some measurements with different JFETs and 
>> BJTs and I didn't find quite big differences.
>   Do not think BJTs in general are that good; try an LED...




Hello Robert :)
Thanks for replying to my post. The main problem with LEDs is their low 
breakdown voltage. I have not measured leakage current of an LED but it 
makes sense because GaAs Reverse saturation current is about 10 times 
less than Si. Have you used LED as an ultra low leakage diode ? have you 
measured leakage currents of LEDs?

Regards,
Ebrahim
Reply by Phil Allison ●June 13, 20092009-06-13
"Ebrahim"


** You are a totally stupid pile of autistic shit, a waste of space a waster
of good people's valuable time.

   Fuck off and DROP DEAD  !!!
Reply by Ebrahim ●June 13, 20092009-06-13
Robert Baer wrote:

> Ebrahim wrote:
>   Do not think BJTs in general are that good; try an LED...


Hello Robert  :)
Thanks for replying to my post. I have not measured leakage current of 
an LED but it makes sense because GaAs Reverse saturation current is 
about 10 times less than Si. Have you used LED as an ultra low leakage 
diode ? have you measured leakage currents of LEDs?

Regards,
Ebrahim
Reply by miso...@sushi.com ●June 13, 20092009-06-13
On Jun 12, 7:06=A0am, Ebrahim <Engineer....@gmail.com> wrote:

> Hello, I want is there anyone that has used a BJT instead of ultra low
> leakage diode(<10pA) in a serious design. The reason that I do not use
> JFET is that I need high breakdown(100V) voltage. So I also need
> Bootstrapping =A0I have down some measurements with different JFETs and
> BJTs and I didn't find quite big differences.


What exactly are you trying to protect? IC, fet, ??
Reply by Ebrahim ●June 13, 20092009-06-13
miso@sushi.com wrote:


> What exactly are you trying to protect? IC, fet, ??


Hello,
I'm  Trying to protect input of Ultra low bias current FET OpAmps.

Regards,
Ebrahim
Reply by Robert Baer ●June 13, 20092009-06-13
Ebrahim wrote:

> Robert Baer wrote:
>> Ebrahim wrote:
>>> Hello, I want is there anyone that has used a BJT instead of ultra 
>>> low leakage diode(<10pA) in a serious design. The reason that I do 
>>> not use JFET is that I need high breakdown(100V) voltage. So I also 
>>> need Bootstrapping  I have down some measurements with different 
>>> JFETs and BJTs and I didn't find quite big differences.
>>   Do not think BJTs in general are that good; try an LED...
> 
> 
> 
> Hello Robert :)
> Thanks for replying to my post. The main problem with LEDs is their low 
> breakdown voltage. I have not measured leakage current of an LED but it 
> makes sense because GaAs Reverse saturation current is about 10 times 
> less than Si. Have you used LED as an ultra low leakage diode ? have you 
> measured leakage currents of LEDs?
> 
> Regards,
> Ebrahim

   In a way i have "measured" leakage current in LEDs; low microamps for 
remaining visibility which i think is astounding, and <1nA in the 1V 
(forward) region with corresponding reverse values.
   Certainly not in the region you want.