Shunt-Thru - Omicron Lab Bode 100 User Manual

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
toperform 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