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Spectrum Analyzer Doubles As Phase-Noise Test Set

This new line of analyzers provides all the tools and performance of a dedicated phase-noise test set with superb spectrum-analysis capabilities through 50 GHz.

Spectrum analyzers are versatile test tools capable of displaying wide-dynamic-range signals over broad frequency ranges. The new FSUP Signal Source Analyzers from Rohde & Schwarz (Columbia, MD) goes beyond traditional spectrum analyzers, however, by including the equivalent of a phase-noise test set. Available in models operating from 10 MHz to 8.0 GHz, 10 MHz to 26.5 GHz, or 10 MHz to 50 GHz, the FSUP Signal Source Analyzers combine superb performance with fast and easy operation.

The FSUP Signal Source Analyzers (see figure) builds on the company's successful FSU spectrum-analyzer platform, incorporating additional phase-noise measurement capability. It operates in two different measurement modes, as a spectrum analyzer or as a signal source analyzer. In the latter mode, it provides phase-noise measurements with the spectrum analyzer, phase-noise measurements with a phase comparator, and phase-noise measurements with a phase comparator and cross correlation. The FSUP works with either its internal reference oscillator or a usersupplied external reference source. The instrument is a powerful oscillator test tool, capable of a wide range of measurements on tunable oscillators, including testing of voltage-controlled-oscillator (VCO) tuning characteristics, VCO DC characteristics, VCO RF power characteristics, tuning sensitivity, VCO pushing, and harmonic power.

It backs these measurements with unrivalled performance and accuracy, such as a dynamic range defined by a displayed average noise level (DANL) of -160 dBm and third-order intercept point of +25 dBm. To reliably measure the phase noise of high-frequency oscillators, the FSUP analyzers incorporate a low-noise internal reference source capable of -134 dBc/Hz phase noise offset 10 kHz from a 1-GHz carrier and -170 dBc/Hz phase noise offset 10 MHz from the same carrier. Spurious levels are -80 dBc to 8 GHz, -68 dBc to 26.5 GHz, and -62 dBc to 50 GHz. Option FSUP-B60 provides the FSUP analyzers-with two parallel receive paths to perform phase-noise measurements with cross correlation between the two paths. This eliminates the uncorrelated noise that is inherent in internal reference sources and improves the dynamic range by as much as 20 dB.

The FSUP Signal Source Analyzers feature resolution-bandwidth filters with 3-dB bandwidths from 10 Hz to 20 MHz as well as a 50-MHz-wide filter. They also include electromagnetic-interference (EMI) filters with 6-dB bandwidths of 200 Hz, 9 kHz, and 120 kHz, as well as Fast Fourier Transform (FFT) digital filters with 3-dB bandwidths of 1 Hz to 30 kHz. Video (3-dB) bandwidth filters range from 1 Hz to 10 MHz. Frequency resolution is 0.01 Hz in both measurement modes. The FSUP analyzers can display amplitude levels from the DANL to +30 dBm.

Test results are shown on an 8.4-in. (21 cm) LCD TFT screen with 800 x 600-pixel SVGA resolution. Options include 0-to-30-dB electronic attenuation, a 20-dB-gain preamplifier, and ports for external mixers which can extend measurement capabilities to 110 GHz. The FSUP analyzers include Ethernet (RJ45), Universal Serial Bus (USB), RS-232C serial port, and GPIB interfaces. Rohde & Schwarz, Inc., 8661A Robert Fulton Dr., Columbia, MD 21046; (410) 910-7836, FAX: (410) 910-7801, Internet:

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