The admittance measurement system is used to determine the complex admittance (or its inverse, the impedance) of an electronic device for a range of frequencies (100 mHz - 100 kHz) and dc biases. Devices are mounted in the probe station inside a Lindgren RF-shielded enclosure (metal room in background). Instruments are controlled over the GPIB by a personal computer (on left). Voltage bias is furnished by a Hewlett-Packard model 4140B voltage source (on right end of red table). Impedance is measured by Hewlett-Packard model 3562A dynamic signal analyzer (on cart to right) using its swept-sine mode. DC and AC signals are sent through feed-thrus into the RF-shielded enclosure where they are put together in summing and buffering amplifiers designed and built at Oberlin by students in collaboration with Bill Mohler, the science-division electronics specialist.
The voltage across the device-under-test (DUT) along with the output of a current-to-voltage converter (inside the shielded room) are brought out of the shielded room and measured by the Keithley model 199 scanner/dmm (center).