Keithley Instruments Inc. reported at time of introduction that its Model 6221 ac/dc current source was the only commercially available current source waveform generator, and that engineers and researchers previously had to build their own ac current sources.

Model 6221 not only provides better accuracy, consistency, reliability, robustness, and cost effectiveness than homemade solutions, but also simplifies creating and outputting complex waveforms. Pulse widths as short as 5 microseconds can be programmed, and the instrument supports pulsed I-V measurements.

In addition, Model 6221 combines ease of use with exceptionally low current noise. Low current sourcing is critical to applications in test environments, ranging from R&D to production, and especially in the semiconductor, nanotechnology, and superconductor sectors.

It's also fully programmable via the front panel controls or from an external controller via RS-232 or GPIB interfaces. Model 6221 features an Ethernet interface for remote control, can source dc currents from 100 fA to 100 mA, and can source ac currents from 1 pA to 100 mA.

Model 6221 has tools for defining current ramps, and stepping through pre-defined sequences of up to 64,000 output values using a trigger or a timer. It supports linear, logarithmic, and custom sweeps. Model 6221's high source resolution and megahertz update rates produce high-fidelity current signals indistinguishable from analog current ramps. www.keithley.com

• Sources ac currents from 1 pA to 100 mA
• Sources dc currents from 100 fA to 100 mA
• Arbitrary waveform generator to 100 kHz
• Built-in Ethernet connection