Scope Scrutinizes 20 GHz Across Four Channels

Test instrument upgrades, when done thoughtfully, can bring significant new measurement capabilities to the marketplace. Such is the case with the WaveMaster 8Zi-A digital oscilloscopes, serial data analyzers, and disk-drive analyzers from LeCroy Corp. A follow-on to the 8Zi series launched a year and a half ago, these new instruments span 4 to 45 GHz using a single hardware platform. They provide sample rates to 120 GSamples/s at 45 GHz for one channel, 80 GSamples/s at 25 to 30 GHz on two channels, and 40 GSamples/s on all four channels from 4 to 20 GHz (with an option to increase the sampling rate to 80 GSamples/s on two channels from 4 to 20 GHz). Acquisition channel capability can be doubled on all models by using the Zi-8CH-SYNCH Oscilloscope Synchronization Kitwith all acquired channels displayed on a single display grid.

At the heart of the WaveMaster 8Zi-A models are second-generation silicongermanium (SiGe) components. The SiGe chipset provides bandwidth to 20 GHz without utilizing the DSP "bandwidth boosting" techniques that are used for four-channel/20-GHz oscilloscopes from other manufacturers. In addition, the 25-to-45-GHz 8Zi-A models make use of sixth-generation Digital Bandwidth interleave (DBI) functionality to extend their bandwidths. The oscilloscopes minimize signal-fidelity problems by achieving total jitter noise below 190 fs rms (20 GHz) or 125 fs rms (45 GHz). When compared to the earlier 8Zi series oscilloscopes, the signal-to-noise performance of the new WaveMaster 8Zi-A models is improved by approximately 25 percent, thanks to the new SiGe chipset.

By leveraging SiGe track-and-hold (T/H) and analog-to-digital (ADC) components, the 845Zi-A is able to provide bandwidth of 45 GHz in single-channel mode. This oscilloscope also can be operated in a 30-GHz/two-channel or 20-GHz/four-channel mode. This aspect gives designers the flexibility to utilize multiple channels at 30 or 20 GHz for timing validation while retaining the ability to utilize fewer channels for higher-bandwidth signal-fidelity measurements. At 45 GHz, it provides a noise floor of 125 fs rms. The oscilloscope's maximum sample rate in single-channel mode is 120 GSamples/s (45 GHz) with 80-Gsample/s and 40-Gsample/s operation in two-channel (30-GHz) and four-channel (20-GHz) modes, respectively (see figure).

In terms of analysis, the WaveMaster 8 Zi-A comes standard with an Intel Core 2 Quad processor running at a clock speed of 3 GHz (with an effective 4 x 3 GHz = 12 GHz processing speed). The oscilloscope also includes 8 GB of RAM and the Windows 7 64-bit operating system. The X-Stream ii streaming software architecture uses variable waveform segment lengths to improve centralprocessing- unit (CPU) cache-memory efficiency to fully leverage the quad-core processor and provide fast and full analysis memory processing up to 768 Mpoint waveforms. Standard memory on all 8 Zi-A oscilloscope models has been increased from 10 to 20 mpoints/channel and from 20 to 32 mpoints/channel on the SDA and DDA models. Memory options to 256 Mpoints/channel are available. In 120- and 80-GSample/s mode, memory can be interleaved to 768 and 512 mpoints/channel. The highest-bandwidth SDA 845Zi-A model comes standard with 96 mpoints/ channel memory at 45 GHz. Pricing starts at $268,000.NF

LeCroy Corp., 700 Chestnut Ridge Rd., Chestnut Ridge, NY 10977-6499; (845) 425-2000, FAX: (845) 578-5985, www.lecroy.com.