Product category:
Stand-Alone Instruments
News Release from: Keithley Instruments | Subject: Model 6487
Edited by the Electronicstalk Editorial
Team on 21 November 2002
Picoammeter provides femtoamp resolution
Keithley Instruments reckons its Model 6487 picoammeter/voltage source provides a set of measurement capabilities unique in the industry.
Keithley Instruments reckons its Model 6487 picoammeter/voltage source provides a set of measurement capabilities unique in the industry These include low current sensitivity near that of an electrometer, with ease of use and pricing comparable to a high performance DMM
This article was originally published on Electronicstalk on 19 Jun 2008 at 8.00am (UK)
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The Model 6487 is a 5.5-digit instrument that can apply a voltage stimulus as high as 500V to a device under test (DUT) and measure currents as low as 20fA.
It also provides direct readout of resistance measurements up to 5x10e16ohm using the source voltage, measure current method, including an alternating voltage method to minimise background current errors.
With a data acquisition rate of 1000 readings/s into buffer memory, there is no faster picoammeter available.
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These features result in the most cost-effective solution available for applications such as ion beam current measurements, radiation monitoring, characterisation of optoelectronic and semiconductor devices, optical fibre alignment, and high resistance material screening.
There is a growing need for low DC current measurements on materials and devices that also require stimulation by a voltage source.
Typical measurements include insulation resistance, leakage currents, photodiode and photomultiplier tube currents, SEM beam currents, sensor characterisation, and I/V characterisation of semiconductors and other components.
The Model 6487 will also be of interest to OEMs and system integrators who require voltage stimulated low-level current measurements in their test systems.
The ability of the Model 6487 to measure currents less than 100nA accurately is something that even high performance DMMs cannot do because of sensitivity, voltage burden, and cabling limitations.
Although electrometers (a more sensitive class of instrument) can measure low currents very accurately, their versatility and extremely high precision circuitry increases their cost significantly.
The Model 6487 is significantly less expensive than other instruments that perform similar functions, such as optical power meters, tera-ohmmeters, user-designed solutions, and competitive products with fewer functions.
The Model 6487's 20fA sensitivity allows characterisation of low-current phenomena, and its 20mA range lets it measure currents high enough for 4-20mA sensor loops.
Its 5.5-digit resolution and voltage burden of less than 200mV on lower measurement ranges allow highly accurate measurements, even in circuits with low source voltages.
A built-in Keithley Model 487 emulation mode simplifies upgrading existing applications.
Furthermore, the Model 6487 can take abusive overloads up to 505V DC (maximum common mode and continuous input).
It is even safe to short the voltage source into the picoammeter.
The voltage source ranges are +/-10, +/-50 and +/-500V DC, with a basic accuracy of +/-0.1% on the programmed value.
In addition, an alternating voltage method for high resistance measurements is available that reduces errors due to externally generated background currents.
For all measurements, a time-stamped 3000-reading data buffer provides minimum, maximum, and standard deviation statistics.
A rel function permits making relative readings with respect to a baseline value; the log function displays the logarithm of the absolute value of the measured current.
The Model 6487 is designed for easy connection to other instruments and voltage sources with a built-in trigger link interface that allows synchronising two or more instruments.
This interface combines six independent selectable trigger lines on a single connector for simple, direct control over all instruments in a system.
An IEEE488 interface is included for controlling the instrument with a PC over the GPIB.
There is also an RS232 interface.
The Model 6487 has triaxial connectors that allow the picoammeter to be used in floating operation up to 500V, but inexpensive BNC cables can be used when appropriate.
To simplify integrating the Model 6487 into PC-based test systems, the instrument comes with Keithley's Excelinx, an add-in utility for Microsoft Excel.
Within minutes of installing Excelinx on a PC, users can acquire data directly from the Model 6487 instrument, and then employ Excel's graphics, charting, and analysis capabilities to turn that data into useful information.
No programming is required to use Excelinx-a few mouse clicks are all it takes.
Keithley also provides a 6487 instrument driver for use with Application Development Environments such as LabView, LabWindowsT/CVI, Visual Basic, C/C++ and TestPoint.
Numerous examples and an online help utility are provided to help programmers get their applications "up and running" quickly. Request a free brochure from Keithley Instruments ...
(This was Electronicstalk's Top Story on 20 November 2002).
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