Re: PAD5
- From: James Arthur <bogusabdsqy@xxxxxxxxxxx>
- Date: Sat, 02 May 2009 01:55:02 GMT
John Larkin wrote:
On Fri, 01 May 2009 16:15:10 -0700, Joerg
<notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:
John Larkin wrote:I just got some samples of a Vishay PAD5 picoamp-leakage diode, inWhat are you going to design with that diode then?
SOT23.
Pin 3 to pin 1 ohms as a diode
Pin 3 to pin 2 ohms as a diode
Pin 1 to pin 2 ohms as an 8K resistor.
Next project is to actually measure the forward and reverse curves,
down to pA levels.
It's the amplifier that's going to operate in vacuum. The signal is
nanovolts at very high impedance, with occasional massive RF blasts. I
was thinking of using them as back-to-back clamp diodes to protect the
front end. Vf is 1.5 volts at 10 mA, so they're not going to protect a
lot.
Their zero-bias resistance should be pretty low, but looks like I'll
have to measure it. That's a nisance at pA levels. Maybe I can get one
of those tins full of Danish cookies...
John
Did you consider using smt LEDs as low-leakage diodes? (painted,
of course)
Electrometer-grade JFETs are another source of low-leakage diodes.
I seem to remember that's what some of the PADs series are--JFETs.
Cheers,
James Arthur
.
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