The Keithleyt 6221 AC/DC Current Source Meter 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, especially in the semiconductor, nanotechnology, and superconductor industries. High sourcing accuracy and built-in control functions make the 6221 ideal for applications like hall measurements, resistance measurements using delta mode, pulsed measurements, and differential conductance measurements.

The Need for Precision, Low-current Sourcing

Device testing and characterization for today's very small and power-efficient electronics requires sourcing low-current levels, which demands the use of a precision, low-current source. Lower stimulus currents produce lower - and harder to measure - voltages across the device.

AC Current Source and Current Source Waveform Generator

The 6221 is the only low-current AC source on the market. Before its introduction, researchers and engineers were forced to build their own AC current sources. This cost-effective source provides better accuracy, consistency, reliability, and robustness than "home-made" solutions. The 6221 is also the only commercially available current source waveform generator, which greatly simplifies creating and outputting complex waveforms.

Simple Programming

The 6221 is fully programmable via the front panel controls, or from an external controller via RS-232 or GPIB interfaces; it also features an Ethernet interface for remote control from anywhere there's an Ethernet connection. The 6221 can source DC currents from 100fA to 105mA, and AC currents from 4pA to 210mA peak to peak. Its output voltage compliance can be set from 0.1V to 105V in 10mV steps. Voltage compliance (which limits the amount of voltage applied when sourcing a current) is critical for applications in which overvoltages could damage the device under test (DUT).

Define and Execute Current Ramps Easily

The 6221 offers tools for defining current ramps and stepping through predefined sequences of up to 65,536 output values using a trigger or a timer; it supports linear, logarithmic, and custom sweeps.

The 6221's combination of high-source resolution and megahertz update rates makes it capable of emulating high fidelity current signals that are indistinguishable from analog current ramps.

Figure 1. Perform, analyze, and display differential conductance measurements

Figure 2. Delta mode offers 1000-to-1 noise reduction

Figure 3. The Model 6221 and the free example start-up control software

Pulsed Tests

Even small amounts of heat introduced by the measurement process itself can raise the DUT's temperature, skewing test results or even destroying the device. The 6221's pulse measurement capability minimizes the amount of power dissipated into a DUT by offering maximum flexibility when making pulsed measurements, allowing users to program the optimal pulse current amplitude, pulse interval, pulse width, and other pulse parameters.

The 6221 makes short pulses (and reductions in heat dissipation) possible with microsecond rise times on all ranges.

Standard and Arbitrary Waveform Generator

The 6221 is the only low-current AC source on the market. It can be programmed to generate both basic waveforms (sine, square, triangle, and ramp) and customizable waveforms with an arbitrary waveform generator (ARB) that supports defining waveforms point by point. It can generate waveforms at frequencies ranging from 1mHz to 100kHz at an output update rate of 10 megasamples/second. It can also expand the capabilities of lock-in amplifiers in applications that already employ them. For example, its clean signals and its output synchronization signal make it an ideal output source for lock-in applications such as measuring second and third harmonic device response.