I saw the other day a Keithley 2636B SMU which has 0.1fA resolution @
10uV in a "normal" Keithley DMM box size. Keithley also have some
systems with external amps that go down even further, to tens of
atto-Amp regions. Even the old HP resolves down to 1fA.
It made me curious.
Dear list: What's th
A simplest model is RC integration.
http://electronicdesign.com/test-amp-measurement/whats-all-femtoampere-stuff-anyhow
- Original Message -
Subject: [volt-nuts] How are femto-amps measured?
I saw the other day a Keithley 2636B SMU which has 0.1fA resolution @
10uV in a "n
With modern digital readout meters, this can be very misleading in terms
of actual useable capability. In this case, using the specified highest
sensitivity 100 pA range, and six digits of digital resolution, gives
E-10 A/E6 or E-16 A, which is 100 aA for the last digit. But, looking at
the noi
I'll only add two things. You can believe Keithley's specs for equipment
made prior to their acquisition by Danaher in 2010 or so. You also have to
make these measurements under controlled conditions; for example, but using
a Triax connected Faraday cage, not ever touching what you are measuring
be
A simpler representation.
http://www.edn.com/design/other/4381004/Femtoamp-fA-measurements
Subject: Re: [volt-nuts] How are femto-amps measured?
A simplest model is RC integration.
http://electronicdesign.com/test-amp-measurement/whats-all-femtoampere-stuff-anyhow
in the Flintstones era you would have a bird count the electrons as they
flow down the wire.
On Fri, Jun 5, 2015 at 10:23 AM, MARVIN wrote:
> A simpler representation.
>
> http://www.edn.com/design/other/4381004/Femtoamp-fA-measurements
>
>
> Subject: Re: [volt-nuts] How are f
As described, the pico-femto amp meters are "pass-through", current
goes in AND out, at 10uV burden voltage. They are explicitly not shunt
and as far as I understand, can't be trans-impedance amplifiers
either.
The very lowest leakage OP-amp I know of, LMP7721 is rated 3 fA typ,
with a specified l
Jan Fredriksson writes:
> As described, the pico-femto amp meters are "pass-through", current
> goes in AND out, at 10uV burden voltage. They are explicitly not shunt
> and as far as I understand, can't be trans-impedance amplifiers
> either.
>
> The very lowest leakage OP-amp I know of, LMP7721
Yes, the input DC bias current can be compensated for, as long as it
doesn't change too quickly, or isn't too big to make the input amplifier
circuits run out of dynamic range. In a digital meter environment, all
sorts of auto-zeroing and multi-sloping things and digital signal
processing can b
