Oscilloscope soars to 100GHz bandwidth

Is it technology leadership for the sake of it?

“Absolutely not,” said Kenneth W Johnson, Director of Marketing for Teledyne LeCroy. “There are companies out there who want the bandwidth.” He concedes that it was an expensive exercise to develop the new instrument.

“One of the keys to achieving 100GHz bandwidth was extending our Digital Bandwidth Interleaving (DBI) technology,” he told Electronics Specifier. Essentially the DBI splits an input signal into the multiple frequency bands. It downconverts each band to the bandwidth of the digitising system. It acquires and digitises each band and then uses a DSP to reassemble the bands and compensate for any distortions present. Teledyne LeCroy has used this technique in its earlier high bandwidth oscilloscopes, but Johnson admits it was a challenge to implement on the 100GHz, 240GS/s oscilloscope.

Teledyne LeCroy believes it has handed the keys to analysing and understanding the fastest phenomena found in R&D labs where engineers and scientists are working on next-generation communication systems, high bandwidth electrical components, and fundamental scientific research.

The instrument was recently used by Alcatel-Lucent to demonstrate the highest-bandwidth coherent optical receiver capable of detecting a 160 GBaud QPSK signal.

“As we research new ways to expand the amount of data that future optical communications networks will be expected to carry, we demonstrated a record 160-GBaud QPSK system prototype. The 100-GHz bandwidth and 240-GS/s sampling rate were key in building this system”, says Dr. Peter Winzer of Bell Labs, the industrial research arm of Alcatel-Lucent. “We are excited to see that Teledyne LeCroy has pushed oscilloscope technology to where the oscilloscope’s bandwidth is no longer the limiting factor in our research; it currently exceeds the bandwidth of the transmitter and optical-to-electrical converter in the receiver.”

Since the fastest signals often require custom analysis, LabMaster 10-100Zi comes standard with the XDEV package that allows users to run custom MATLAB scripts in-stream. For a complete analysis of coherent optical signals such as DP-QPSK and DP-16QAM, use the Optical-LinQ optical modulation analysis package.

In addition, SDAIII-CompleteLinQ performs and compares eye, jitter and noise analysis on up to four lanes, simultaneously.

Scientific research of phenomena that occur at the shortest timescales requires the fastest digitisation speeds. At

240 GS/s, samples are acquired at time intervals of 4.17 ps, 50% faster than the next-fastest digitiser, yielding excellent signal reconstruction. Integral to the oscilloscope is Teledyne LeCroy’s patented ChannelSync modular architecture, whereby a single 10GHz clock is distributed to all acquisition modules to achieve 130fs channel to channel jitter.

Telecommunications companies invest heavily in R&D to develop coherent optical technologies using quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM) schemes. In order to

characterise the efficiency of formats such as DP-QPSK and DP-16QAM, high speed digitisers are required.

Demodulated I & Q signals acquired using the LabMaster 10-100Zi may be analysed with Optical-LinQ software,

or using custom scripts, running either in-stream on the oscilloscope, via remote control, or offline.

The Optical-LinQ software developed in partnership with Coherent Solutions, is designed to perform a complete optical modulation analysis on the oscilloscope. Optical-LinQ can analyse I & Q signals from the users’ receiver, or from one of Coherent Solutions’ IQScope-RT Series Coherent Optical Receivers. Optical-LinQ includes a library of DSP algorithms for recovery and reconstruction of I & Q signals, which can then be analysed with a wide range of visualisations and measurements. A LabMaster 10 Zi oscilloscope, IQScope-RT receiver and Optical-LinQ software form a complete OMA solution.