john jardine wrote:

"John Woodgate" wrote in message
news
I read in sci.electronics.design that john jardine
wrote (in
k) about 'Diode and very small amplitude high frequencies signals', on
Sat, 5 Feb 2005:
Test on a 1N4148.
ForwardV DiodeR
+50mV 8megs.
+30mV 9megs.
+20mV 10megs.
+10mv 12megs.
+5mV 21megs.
ReverseV
-5mV 21megs.
-10mV 30megs.
-30mV 270megs.

How did you measure the resistance? Is it an incremental resistance
(slope of the V/I curve at the data point) or the slope of a line
joining the origin to the data point on the curve.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

I didn't measure the resistance. The values just come from the static V and
I plot points on the graph.
Having had my remaining bench DVM, (good ol'e UK, Datron ****e) pack in on
me and 2 battery DVMs keel over with flat batteries and the CMOS buffers
floating off to la la land and 2 crocodile clips secretly fail and finally
my electric pencil sharpener going tits up, I was not of a mind to press
on :-)
regards
john

In other words, this data is just a plot of a diode's DC I vs V
characteristic, right?

What is of more interest is the slope at a given DC operating point. If
we pick 0V, for example, the above data (within the limits of its
precision) gives a flat line around that point (+5mV 21 Mohms, -5mV 21
Mohms). With a 100 uV signal, you might as well throw a 21 M ohm
resistor in there instead.

--
Paul Hovnanian
------------------------------------------------------------------
Think honk if you're a telepath.