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For developing high-quality transmit and receive equipment such as communications and broadcast systems or radar, users have to measure phase noise and perform spectrum analysis. Toward that goal, Rohde & Schwarz's signal source analyzer R&S FSUP combines a high-end spectrum analyzer up to a maximum frequency of 50 GHz with a phase noise tester based on the PLL method into one instrument. In essence, it is the company's first instrument designed for measuring phase noise and characterizing RF signal sources. Frequency range is up to 8/26.5/50 GHz. It can be extended to 110 GHz with external mixers.

Thus, when measuring phase noise, the instrument compares the signal from the device under test with a reference source using its internal reference or an external reference. In addition, the user can select the source for regulating the required 90∞ phase offset on the phase comparator. If desired, the optimum settings for the measurement are selected automatically by the instrument. Together, with other measurement parameters such as bandwidth, filter type and number of averages, the offset frequency range is also easy to configure. At an input frequency of 640 MHz and a frequency offset of 10 kHz, the phase noise value of the R&S FSUP with an internal reference source is -136 dBc/Hz and at 10 MHz frequency offset -165 dBc/Hz. The R&S FSUP-B60 option provides the signal source analyzer with two parallel receive paths. The symmetrical structure allows a cross-correlation between the two paths, which allows the instrument to eliminate the uncorrelated inherent noise of the internal reference sources. This improves the dynamic range by up to 20 dB, depending on the number of averages. The users can mark and list all interference lines or, alternatively, to suppress interference lines. Integral parameters such as residual FM/PM or rms jitter are also displayed.

The phase noise tester can record the level or the frequency of the signal source as a function of time and thus display settling and switching processes at high-frequency sources with high resolution. Thus, the instrument is also able to precisely analyze the behavior of signal sources in the time domain. To measure phase noise or to record VCO tuning characteristics or how the level and frequency vary as a function of the supply voltage, extensive settings of the oscillator's supply and tuning voltage are necessary. The R&S FSUP provides two independent, extremely low-noise dc supply outputs, a negative supply voltage and two tuning voltage sources for this purpose.The high-end R&S FSU spectrum analyzer integrated in the instrument rounds out the functionality of signal source analysis by allowing users to perform measurements on other parameters, such as harmonic suppression, spurious emissions or adjacent-channel power, that are needed for the development and production of high-frequency modules and equipment. Additionally, it can also measure the noise figure with the aid of a noise source and the optional R&S FS-K30 noise measurement software. The special advantage of the integrated spectrum analyzer, however, is mainly that in comparison with other solutions it not only simplifies test sets and makes them more flexible but it also reduces investment costs.

“For developing high-quality oscillators or synthesizers, users always need a spectrum analyzer in addition to the phase noise tester in order to fully test their circuits,” stated Josef Wolf, director of the subdivision for spectrum and network analyzers. “With the spectrum analyzer already integrated in the R&S FSUP, it is no longer necessary to purchase such an instrument. And this also reduces the space required in a test rack in production, for example.”
Rohde & Schwarz
(410) 910-7800