Among other updates, the seventh edition of the Low Level Measurements Handbook incorporates information on the latest electrical measurement tools and techniques, including those developed for characterizing today’s nanoscale devices and high power semiconductors.
Section 1 looks at the expanding range of low level DC measuring finstruments now available to scientists and engineers, including the electrometer, digital multimeter (DMM), nanovoltmeter, picoammeter, source measure unit (SMU) instrument, low current preamp, micro-ohmmeter, and low current source.
DC voltage, DC current, and resistance are measured most often with digital multimeters (DMMs). Generally, these instruments are adequate for measurements at signal levels greater than 1μV or 1μA, or less than 1GW. However, they don’t approach the theoretical limits of sensitivity. For low level signals, more sensitive instruments such as electrometers, picoammeters, and nanovoltmeters must be used.
Section 1 also discusses the theoretical limits of DC measurements and the instruments used to make them. It includes instrument descriptions and basic instrument circuit designs. For easier reference, this information is organized into a number of subsections:
• Theoretical Measurement Limits: A discussion of both the theoretical measurement limitations and instrument limitations for low level measurements.
• Instrument Definitions: Descriptions of electrometers, DMMs, nanovoltmeters, picoammeters, source measure unit (SMU) instruments, SourceMeter® Source Measure Unit (SMU) Instruments, low current preamps, and micro-ohmmeters.
• Understanding Instrument Specifications: A review of the terminology used in instrument specifications, such as accuracy (resolution, sensitivity, transfer stability), deratings (temperature coefficient, time drift), noise (NMRR and CMRR), and speed.
• Circuit Design Basics: Describes basic circuit design for voltmeter circuits, ammeter circuits, coulombmeter circuit, high resistance ohmmeter circuits, low resistance ohmmeter circuits, and complete instrument block diagrams.
Section 2 offers detailed information about various interferences and error sources, and ways to maximize the accuracy of measurements made from high resistance sources. It is organized into these subsections:
• High Impedance Voltage Measurements
• Low Current Measurements
• High Resistance Measurements
• Charge Measurements
• General Electrometer Considerations
• High Impedance Measurement Optimization Summary
Low voltage and low resistance measurements are often made on devices and materials with low source impedance. Therefore, Section 3 describes how to use these instruments to make accurate measurements, including a discussion of various error sources and ways to minimize their effect on measurement integrity:
• Low Voltage Measurements: Discussion of potential error sources and how to minimize their impact on low voltage measurement accuracy. These error sources include offset voltages, noise and common-mode current, and reversal errors.
• Low Resistance Measurements: Topics include lead resistance, thermoelectric EMFs, non-ohmic contacts, device heating, dry circuit testing, and measuring inductive devices.
• Low Impedance Measurement Optimization Summary
Section 4 provides useful information on configuring test setups for a wide range of low level measurement applications. This Section covers a variety of low-level measurement applications:
• Applications for Measuring Voltage from High Resistance Sources
• Low Current Measurement Applications
• High Resistance Measurement Applications
• Charge Measurement Applications
• Low Voltage Measurement Applications
• Low Resistance Measurement Applications
The handbook concludes with an updated instrument selection guide, an illustrated cable and connector assembly guide, glossary, and test system safety reference. A detailed index helps readers find specific topics quickly.
The handbook can be downloaded at no cost athttp://www.keithley.com/promo/wb/1401.
A free sample section of the handbook is also available through Keithley’s online Knowledge Center. For more information, contact the Keithley Instruments, Inc. at 800-688-9951, or email them at [email protected] or at their website, www.keithley.com.