Keithley Instruments, Inc., a manufacturer of advanced electrical test instruments and systems, expands its low-level measurement portfolio by introducing a dual-channel picoammeter with dual +/-30 volt (V) independent, non-floating bias sources and 1 femtoampere (fA) measurement resolution. (A picoammeter, or pico ammeter, measures very low electrical current, usually from the picoampere range at the lower end to the milliampere range at the upper end.) The Model 6482 Picoammeter, the latest addition to Keithley’s line of sensitive instrumentation, provides two independent picoammeter/source channels in a 2 unit (U), half-rack enclosure, allowing simultaneous 6½ digit measurements across both channels. It offers twice the channel density available from other high speed, high accuracy picoammeters for easier control and data aggregation and a lower cost of ownership, as well as higher measurement accuracy (+/-1% on the 2 nanoampere, or nA, range) and a wider dynamic range (1fA to 20mA) than competing single-channel picoammeter/source combinations. At 4½ digit resolution, users can take up to 900 readings per second on each channel.
The Model 6482 offers low current measurement ranges from 2nA to 20mA in decade steps. This wide measurement range ensures high sensitivity and resolution for the growing number of low current applications that require making measurements at multiple points simultaneously.
The Model 6482’s 2nA current measurement range is suitable for measuring dark currents and other low currents with 1fA resolution. When the level of dark current has been determined, the instrument’s relative value (REL) function on the liquid crystal device (LCD) at the directional control valve (DCV) and capacitance functions. The REL function automatically subtracts the dark current as an offset so the measured values are more accurate for optical power measurements. For measuring the dark currents of photodiodes or other light-sensitive components, the Model 6482’s front-panel display can be switched off to avoid introducing light that would interfere with accurate results.
The Model 6482 can provide ratio or delta measurements between the two completely isolated channels. These functions can be accessed via the front panel or the general-purpose interface bus (GPIB) interface. For test setups with multiple detectors, this capability enables targeted control capabilities.
To speed and simplify system integration and control when building multi-instrument test systems that require tightly coupled sourcing and measurement, the Model 6482 provides the Trigger Link feature, as well as standard GPIB and RS-232 interfaces. The Trigger Link feature combines six independent software selectable trigger lines on a single connector for simple, direct control over all of the instruments in a system. This feature is especially useful for reducing total test time if the test involves a sweep. To make it easier to transfer measurement results from the Model 6482 to other instruments, a scaled 0V to 10V analogue output simplifies transmitting data to digital multi-metres (DMMs), data acquisition boards, oscilloscopes, strip chart recorders and other devices.
The Model 6482’s current and voltage limits can be programmed to ensure device protection during critical points such as start of test. It also provides average and median filters, which can be applied to the data stored in each channel’s separate 3000-point buffer memory.
For applications that demand the highest measurement sensitivity, the Model 6482 has rear-panel triaxial inputs for making triaxial cable connections to minimise electrical noise. For less stringent applications, the included triax-to-Bayonet Neill-Concelman (BNC) adapters allow making connections with less costly BNC cables.
The Model 6482 is suitable for a wide range of applications related to characterising electronic materials and devices designed for low current operation in laboratories, research and development (R&D) and manufacturing settings. Applications include:
• Manufacturing component test
• Dual diode testing
• Semiconductor component testing
• Multi-pin component testing
• Dark current measurements
• Ion-beam monitoring
• Electron microscopy
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