www.keithley.com

1.888.KEITHLEY (U.S. only)

A Greater Measure of Confidence

The Model 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.

free Instrument Control Example start-up software

The instrument control example software available for the sources simplifies both performing basic

sourcing tasks and coordinating complex measurement functions with the Keithley Model 2182A . The

software, developed in the LabVIEW® programming environment, includes a step-by-step measure-

ment guide that helps users set up their instruments and make proper connections, as well as pro-

gram basic sourcing functions. The advanced tools in the package support delta mode, differential

conductance, and pulse mode measurements. From this package, users can print out the instrument

commands for any of the pre-programmed functions, which provides a starting point for incorporat-

ing these functions into customized applications.

Differential Conductance

Differential conductance measurements are among the most important and critical measurements

made on non-linear tunneling devices and on low temperature devices. Mathematically, differential

conductance is the derivative of a device’s I-V curve. The Model 6220 or 6221, combined with the

Model 2182A Nanovoltmeter, is the industry’s most complete solution for differential conductance

measurements. Together, these instruments are also the fastest solution available, providing 10

× the

speed and significantly lower noise than other options. Data can be obtained in a single measure-

ment pass, rather than by averaging the result of multiple sweeps, which is both time-consuming and

prone to error. The Model 622X and Model 2182A are also easy to use because the combination can

be treated as a single instrument. Their simple connections eliminate the isolation and noise current

problems that plague other solutions.

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

Delta Mode

Keithley originally developed the delta mode method for making low noise measurements of voltages

and resistances for use with the Model 2182 Nanovoltmeter and a triggerable external current source.

Essentially, the delta mode automatically triggers the current source to alternate the signal polarity,

then triggers a nanovoltmeter reading at each polarity. This current reversal technique cancels out

any constant thermoelectric offsets, ensuring the results reflect the true value of the voltage.

This same basic technique has been incorporated into the Model 622X and Model 2182A delta

mode, but its implementation has been dramatically enhanced and simplified. The technique can

now cancel thermoelectric offsets that drift over time, produce results in half the time of the previ-

ous technique, and allow the source to control and configure the nanovoltmeter, so setting up the

measurement takes just two key presses. The improved cancellation and higher reading rate reduces

measurement noise to as little as 1nV.

ordering Information

6220 DC Precision Current source

6221 aC and DC Current source

6220/2182a

Complete Delta Mode

system, w/DC Current

source, Nanovoltmeter,

and all necessary cables

(GPIb cables not included)

6221/2182a

Complete Delta Mode

system, w/aC and DC

Current source, Nanovolt-

meter, and all necessary

cables (GPIb cables

not included)

accessories supplied

237-alG-2 6.6 ft (2m), low Noise,

Input Cable with Triax-

to-alligator Clips

8501-2

6.6 ft (2m) Trigger link

Cable to connect 622x

to 2182a

Ca-180-3a Ethernet Crossover

Cable (6221 only)

Ca-351

Communication Cable

between 2182a and 622x

Cs-1195-2 safety Interlock

Connector

Instruction manual on CD

Getting started manual (hardcopy)

software (downloadable)

aCCEssorIEs aVaIlablE

7006-*

GPIB Cable with Straight-On Connector

7007-1

Shielded IEEE-488 Cable, 1m (3.3 ft)

7007-2

Shielded IEEE-488 Cable, 2m (6.6 ft)

7078-TRX-5 5 ft (1.5m), Low Noise, Triax-to-Triax Cable

(Male on Both Ends)

KPCI-488LPA IEEE-488 Interface/Controller for the PCI Bus

KUSB-488B IEEE-488 USB-to-GPIB Interface Adapter

sErVICEs aVaIlablE

6220-3Y-EW

1-year factory warranty extended to 3 years from

date of shipment

6221-3Y-EW

1-year factory warranty extended to 3 years from

date of shipment

C/6220-3Y-ISO 3 (ISO-17025 accredited) calibrations within 3

years of purchase*

C/6221-3Y-ISO 3 (ISO-17025 accredited) calibrations within 3

years of purchase*

*Not available in all countries

6220

6221

DC Current Source

AC and DC Current Source