Electronic Design

60-GHz Communications Analyzer Delivers Integrated Test For 40-Gbit Systems

Capable of both time and frequency domain analysis, the instrument exploits synchronous sampling to capture signals more cleanly.

Achieving a 60-GHz bandwidth in a sampling oscilloscope would be an impressive achievement on its own. Lowering the noise floor to −80 dBm over the same bandwidth would also be a notable feat for a dedicated communications analyzer. The MCA1060 Microwave Communications Analyzer, a fully integrated test system for 0.01- to 40-Gbit/s signals, does both as it provides a variety of analyses in both time and frequency domains (see the figure).

The instrument performs spectrum analysis, broadband time-domain-reflectometry (TDR) analysis, and fully error-corrected transmission and return-loss measurements. For time-domain measurements, the MCA1060 displays data in linear- and eye-diagram formats. For frequency-domain tests, users can select log magnitude, Smith-chart, polar, or group-delay modes.

Among the unit's standard features are two 60-GHz input channels, a 6.25-to 200-MHz TTL output, a 6.25-MHz to 1.6-GHz ECL output, and an impulse output with frequency content from 6.25 MHz to 60 GHz. Plus, there are GPIB, VGA, and Centronics ports and connections for a 10-MHz reference input/output. Data can be viewed on the analyzer's built-in display—a 6.4-in. active-matrix color TFT—or on an external VGA monitor.

The MCA1060's performance rests on a proprietary method of synchronous sampling that captures signals more cleanly than was previously possible. Sampling oscilloscopes have traditionally relied on triggering techniques in which a single sample of the signal is acquired following each trigger. Every time the instrument triggers, the delay time between the trigger and event sample is incremented. Eventually, a record of the test signal is built up. This technique requires a repetitive signal and a very stable trigger.

A different method of signal acquisition is employed by the analyzer. Signals must still be repetitive, but a trigger isn't required. Instead, the instrument synthesizes a sample rate that's synchronous to the signal under test. This sample rate extends up to 1.6 Gsamples/s.

The acquired data is an integer number of evenly spaced points/test-signal cycle. Results may either be displayed graphically or analyzed by one of the unit's math programs. LeCroy's ap-proach to signal sampling eliminates trigger-bandwidth limitations, the effects of trigger jitter, and the need for clock regeneration.

Furthermore, the analyzer combines this sampling technique with an impulse-based stimulus containing wideband frequency components. This approach speeds measurements so that signal acquisition and analysis operations—which might require several seconds with other communications analyzers—may be executed in only a fraction of a second.

The MCA1060 doesn't contain a calibrated optical-reference receiver. Even so, the instrument's combination of signal capture and analysis capabilities enable it to test optical modulator sources and receivers as well as fiber cables.

The instrument accepts a maximum CW input of 0 dBm, or an impulse of 225 mV at 50 Ω. Recommended input power is −20 dBm over much of the unit's frequency range, decreasing to −40 dBm at the high end of the range. With averaging, the noise floor can be reduced to −120 dBm across the analyzer's measurement range. In addition, a built-in frequency synthesizer provides a frequency resolution of up to 0.0000002 Hz.

When working in the time domain, the MCA1060 can measure rise and fall times to 6 ps. Plus, it can quantify time delay, pulse width, amplitude, and wander with femtosecond resolution. DC drift is specified as 2 mV/°C and system phase noise is less than 2 ps without averaging. Operating from a 115-V ac source, the unit consumes 250 W. The instrument measures 19 by 8.75 by 15 in. and weighs 35 lbs.

Several Output Types
Additionally, users can output data via the GPIB port or disk by employing the unit's built-in 3.5-in. floppy drive. Data may be output as Spice piece-wise-linear stimulus and circuit files, S-parameter data for Touchstone, or Eagleware.CKT files for Eagleware applications. There are printer output drivers for the HP Laser Jet and Epson Stylus Color printers, too.

LeCroy offers three clock source options for the Microwave Communications Analyzer. They are the CS10, a 10-GHz source; the CS20, a 20-GHz source; and the CS-40, a 40-GHz source. A related option is the Model CS1632 clock doubler. When it's connected to an ECL frequency synthesizer with a 6.25- to 1600-MHz output, this model produces a 12.5- to 3200-MHz ECL output.

Also, there's the Model PG10, a 10-Gbit pseudorandom pattern generator. The company also provides the Model SA sync adapter, which generates an external trigger up to 60 GHz. This adapter is only required when measuring signals from systems are unable to accept or provide a 10-MHz reference.

Other options include 50-Ω and open/short terminations in 1.85-mm "V" female and 2.92-mm "K" female formats, as well as semirigid cable assemblies and reflectometers.

Price & Availability
The MCA1060 is priced at $39,900. The 10-, 20-, and 40-GHz clock sources are priced at $3000, $3000, and $4000, respectively, while the 10-Gbit pattern generator costs $9200. Delivery is eight weeks ARO.

LeCroy Corp., 700 Chestnut Ridge Rd., Chestnut Ridge, NY 10977-6499; contact the Customer Care Center at (800) 453-2769; www.lecroy.com.

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