Thrive on variation
01 August 2006
New avenues for test equipment may create some unusual applications and test the ingenuity of designers, writes TOM BRESLIN
One of the neglected areas for test and measurement is that of semiconductor material R&D. Pulse/pattern generators can be used for device and material research and characterisation and also in nanotechnology projects for advanced materials research. Pulse generators are used for any applications that are driven by a reduction in material size and an increase in operating speeds, for example, nanotechnology and serial communications. They are more conventionally used in specialised applications for characterisation and transient analysis and in applications from data and clock simulation to functional testing for high-speed serial components.
The Series 3400 Pulse/Pattern Generator from Keithley Instruments (www.keithely.com) offers pulse width control from three nsec to 1,000sec. The 3401 is a single-channel, 165MHz pulse/pattern generator and the 3402 is a dual-channel, 165MHz pulse/pattern generator.
With these levels of signal accuracy and control, the generators can offer pulse fidelity with precision edge control for precision testing of components and material characterisation. The signals also have less voltage over-shoot than previous models. This results in a cleaner, more reliable signals for amplitude accuracy and flatness and less edge-to-edge jitter, claims the company. These combine to give greater pulse control for measurements.
The instruments set critical parameters for specific applications, including amplitude, rise time, fall time, pulse width and duty cycle, frequency, delay and offset. They also have a maximum frequency of 165MHz with a minimum frequency down to 1mHz and pulse amplitudes of +/- 10 or 20V. The minimum attainable pulse width of three nsec is specifically for nanotechnology material research. The 3400 series instruments integrate with digital multimeters, source-measure units, semiconductor characterisation systems and oscilloscopes. Multiple user connections, for example GPIB and USB, to increase the integration possibilities and to ease set-up.
The ability to view information on a PC frees engineers for remote analysis. An instrument can acquire data and transfer the file for analysis elsewhere. Tektronix (www.tektronix.com) offers RSAVu off-line analysis software to acquire signals using the company’s Real-Time Spectrum Analyzer (RSA) analyse the information off-line on a PC.
The spectrum analysers are targeted at digital RF applications, including software-defined radios with their complex modulation techniques with its time-varying and pulsed RF signals and RFID that uses momentary communication links. The PC-based software, claims the company, provides the same analysis as the physical Real-Time Spectrum Analyzer, so that files can be captured on one instrument and shared with multiple PC users for off-line analysis. It has identical analysis functionality to that of the company’s RSA3300A, RSA3408A and WCA200A Real-time Spectrum Analyzers. The software can be downloaded, free of charge, from the company website and activated with a USB software key. Microsoft Windows XP or Windows 2000 OS is required.
The combination of the analyser and the software will probably be used by education departments. Tutors can demonstrate and explain transient RF effects, capturing a signal on an RSA for students to analyse signals on their PCs using the software. Out of the classroom, the software can analyse the captured signal at a desk, freeing the instrument for other engineers.
For PCs that are too small to accommodate a PCI card, there are USB devices. USB multi-function devices, data collection can be moved to different PCs to simplify data collection and use. Designed for the USB bus, two external data acquisition (DAQ) devices have been added to the M Series by National Instruments (www.ni.com) to add USB plug and play connectivity and high-speed signal steaming to the M Series. The NI USB-6251 and USB-6259 offer up to 32 analogue input channels and data acquisition rates up to 1.25Msmple/sec.
The company claims that they will set a performance benchmark for USB data acquisition measurements, increasing performance by a factor of five, compared to previous devices. M Series features, such as 32, 16bit, 1.25Msample/sec analogue input channels, four 16bit, 2.8Msample/sec analogue output channels, 32 clocked and correlated digital IO channels and two timing counters, are included in the USB devices.There is also an integrated terminal block, for direct signal connectivity and third order calibration correction at all ranges for accuracy.
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