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Impedance Calibration Standard?

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Joined: July 19th, 2013, 10:45 am
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Impedance Calibration Standard?

Post by dgross » July 19th, 2013, 10:53 am

I'm having some issues resolving a discrepancy between a Keithley 590 CV meter and an Agilent E4980A Precision LCR meter.

I'm doing low-frequency measurements of wafer-level devices in the 100-200 fF range. There is a discrepancy of some 100 fF between the two instruments that doesn't seem to do be due to stray capacitances, cabling issues, etc. Both setups use the same test signal level, etc.

Does Keithley offer some kind of impedance standard (akin to Cascade's Impedance Standard Substrates) for this 100-200 fF range? Cascade offers 50 Ohm standards at 60 fF, 440 fF, 860 fF. If these are not available, does Keithley have some kind of custom solution (for instance, an MOS capacitor test structure?) that has been used to verify the correctness of the 590 product?

Dale C
Keithley Applications
Keithley Applications
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Joined: June 10th, 2010, 6:22 am
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Re: Impedance Calibration Standard?

Post by Dale C » July 23rd, 2013, 3:00 pm

Keithley “used” to have some standard capacitors for this type of verification. But no more.
The lowest capacitance value was 0.47pF. But no matter they are obsolete and there are none left in stock.
The Model 590 and these capacitors went obsolete in 2007.
The Model 590 is still serviced( repair and calibration).

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