Omicron Lab Bode 100, User Manual, Page: 64 / 133

Congratulations you have successfully used the B-WIC impedance measurement adapter with the
Bode 100 . You can load the settings for the measurement by clicking File → Open → and then
navigating to: "%APPDATA%\OMICRON Lab\Bode Analyzer Suite\Demo Files\" .
The file you will need is: ImpAdapt_Inductor.bode3 .
Attention: Since your setup will be different the file should only be used to explore the different
measurement formats offered by Bode 100 . Before you execute an own measurement you will have
to perform a new calibration .
For a detailed measurement example using the impedance adapter measurement mode to
measure capacitors, please check out the ESR measurement application note at
www.omicron-lab.com/BodeManualAppNotes
7.4.3 Shunt-Thru
The Shunt-Thru measurement mode is especially suitable to measure very small impedance values. It
is basically an S21 transmission measurement in a special configuration. The impedance is calculated
from the measured S21 parameter.
Measurement information
Bode 100 measures S21 gain and calculates impedance Z using the equation:
The Shunt-Thru measurement configuration emulates a 4-wire kelvin connection. The output drives a
current thru the device under test that is shunted between the output signal and GND. Channel 2
measures the voltage drop that occurs at the DUT. This measurement mode offers highest sensitivity
for low-impedance value DUT. The recommended impedance measurement range starts at roughly
1 mΩ. With amplifiers or pre-amplifiers also µΩ measurements can be performed.
Shunt-Thru measurement configuration offers low sensitivity for high impedance DUTs. It is not
recommended to measure impedance values much higher than 100 Ω.
The Shunt-Thru configuration inherently suffers a ground-loop error at low frequencies. The
current flowing thru the cable shield of the connection to Channel 2 ground introduces a
measurement error that can become significant at frequencies below 10 kHz when
measuring very low impedance values. To suppress respectively reduce the ground-loop
error at low frequencies, use a common-mode choke or common-mode transformer.
64 OMICRON Lab