TUTORIAL T12


Achieving Accurate and Reliable Low Level Electrical Measurements

 

Presenter Name
Jennifer Makupson

 

Affiliation
Keithley Instruments

 

Photograph

 

Biography
Jennifer Makupson is an Applications Engineer with Keithley Instruments. On a daily basis, she assists Keithley customers in overcoming measurement challenges and provides input on next-generation instrumentation. She received her BSEE from Case Western Reserve University in Cleveland, Ohio, USA.

 

Abstract
This tutorial offers the participants the skills to identify low level measurements and to relate an electrically measured quantity to the physical property of interest.

At the conclusion of the tutorial, participants will be able to identify and explain fundamental limitations and non-idealities of basic electrical measurements, as well as the techniques to address them. In pursuit of this goal, the tutorial will include a discussion of the Johnson Noise equation as a primary method of determining the finite limit of voltage and current measurements. 

The presenter will provide an overview of common sources of error in test environments. Participants will understand how to negate offset voltages and avoid the effects of temperature fluctuations when making low voltage measurements. The tutorial describes the use of current reversal techniques in low resistance measurements to compensate for thermoelectric voltage errors.

The presentation will also consider techniques for making successful low current and high impedance measurements.  As an introduction, participants will learn about common measurement mistakes, including contamination and the use of improper cables, and their impact on test results.  The presenter will show how guarding and shielding are effective in reducing leakage currents due to imperfect insulators and in eliminating interference from radio frequency, electromagnetic, and electrostatic sources.  The tutorial will present an example of how these methods are combined to yield femtoamp-level current measurements. 

To link the theoretical with the practical, throughout the tutorial, the presenter will show how real instrumentation differs from ideal.  Participants will learn how to evaluate their individual instrumentation based on specifications and make the best of available test equipment to maximize measurement accuracy. 

 

Target Audience:
This tutorial is intended for research and industry professionals who need to make low level electrical measurements. Although participants aren’t assumed to have a background in electrical engineering, knowledge of Ohm’s Law is required. A background in an engineering or physics discipline would also be helpful. The presenter welcomes participants from such inter-disciplinary fields as MEMs, nanotechnology, and electrical-base sensor development.