NIST-developed wideband sampling voltmeter provides increased accuracy to calibration laboratory customers.

A wideband (10 Hz to 1 GHz) sampling voltmeter (WSV) has been developed that greatly improves NIST's ability to perform accurate measurements of various electrical waveform parameters. Three replicas of this instrument have been delivered to the sponsors of this work for use in their calibrations laboratories. One WSV unit is being used by Sandia National Laboratories to characterize pulse response of oscilloscopes at peak amplitudes up to 100 V. Accuracy requirements precluded the use of commercial equipment for these measurements. At the Army and Air Force's primary metrology laboratories, two other units are being used to measure the ac gain flatness of state-of-the-art commercial ac voltmeters and calibrators at frequencies up to 30 MHz. The combination of wide bandwidth, large dynamic range, and high accuracy requirements make these measurements extremely difficult to perform. The two laboratories began using the NIST WSV after failing to meet their goals with traditional thermal transfer technology. A fourth WSV is being used at NIST in the pulse calibration service, and a fifth will be used soon in a distorted power calibration service.

The instrument consists of a mainframe unit and a set of two sampling comparator probes. Two types of probes have been developed. One probe type is designed for the sampling of high-speed signals in a 50 [ohm] environment, and the other for the sampling of lower bandwidth signals in a high impedance environment. A key feature of both probe types is that their gain flatness response may be conveniently characterized using step response techniques. Several instrumentation manufacturers have expressed interest in the commercialization of the WSV.

CONTACT: Jerry Stenbakken, [phone]; [e-mail].