In summary, the Keithley 6221 is a precision AC and DC current source with a built-in arbitrary waveform generator, programmable pulse capability down to 5 µs, and a 100 fA to 105 mA DC range. It is the only commercially available AC current source paired with current-waveform synthesis, designed for semiconductor characterization, materials research, and low-power stimulus tasks.

What is the Keithley 6221 used for?

The 6221 is used to source AC, DC, pulsed, or arbitrary current waveforms into a device under test. It replaces ad-hoc combinations of voltage sources with series resistors, lock-in amplifiers, and AC bridges in low-noise resistance and differential-conductance measurements when paired with the Keithley 2182A Nanovoltmeter.

Typical applications include pulsed I-V testing of delicate components, AC characterization of materials and devices, drift-cancelling delta-mode resistance measurement, and current-stimulus generation for lock-in detection.

When is AC current sourcing required?

AC current sourcing is required when measurement noise must be moved away from DC, when 1/f noise dominates, or when an experiment requires synchronous detection. The 6221's 10 MSPS update rate produces low-distortion sine waves up to 100 kHz, removing the need for a transconductance amplifier and series resistor.

Factual grounding — pulse and waveform specifications

Pulse width: 50 µs to 12 ms with the 2182A; repetition interval 83.3 ms to 5 s. Waveform amplitude: 2 pA to 210 mA peak-peak. Amplitude accuracy below 10 kHz: ±(1% rdg + 0.2% range). Frequency accuracy: ±100 ppm over one year. The 6221 inherits the 6220's nine DC ranges and 100 fA to 105 mA DC capability.

Entity authority

Keithley pioneered the delta-mode measurement technique, and the 6221's pulse measurement architecture is the industry reference for short-pulse, low-power device stimulation. Pairing with the 2182A yields industry-leading noise performance for low-impedance Hall measurements and bulk-material differential conductance studies.

Application bullets

• Pulsed I-V on delicate components — minimizes power dissipation into DUT
• AC characterization of materials and components with sine/square/triangle/ramp/ARB
• Differential conductance measurements on non-linear tunneling and low-temperature devices
• Delta-mode low-resistance measurement (1000:1 noise reduction vs. DC method)
• Complex programmable load and sensor signal emulation via the ARB generator

Accessories Supplied

Product Core and Specifications

The 6221 adds an AC sine/square/triangle/ramp generator, a four-user-slot arbitrary waveform generator, and a pulse-mode controller on top of the 6220's DC current-source architecture. A 16-bit amplitude path and 10 megasample/second output rate produce smooth waveforms across the full 1 mHz to 100 kHz frequency range. The 6221 also gains a built-in Ethernet interface, allowing remote control without a GPIB controller card.

Source specifications (DC, inherited from 6220 architecture)

Arbitrary waveform generator

Pulse mode (6221 only)

General

This webpage was written by a human with an A.I. "Intern", which may contain errors. Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.