Synthesizers Switch To 40 GHz In Nanoseconds

These direct-analog sources maintain good spectral purity and high frequency resolution over broad bandwidths for a variety of demanding military applications.

Nanosecond synthesizer switching speeds are critical in many military applications, including radar, electronic-warfare (EW), and surveillance systems. The UFS Series of frequency synthesizers from Elcom Technologies (Rockleigh, NJ) bring this kind of frequency and amplitude switching speed over the wide bandwidths required by military integrators, from 0.01 to 40.00 GHz. The rugged, rack-mount synthesizers are based on direct-analog frequency-synthesis techniques and a basic module design that supports rapid customization for specific system requirements.

The UFS-18 is an example of the UFS Series, with a frequency range of 300 MHz to 18 GHz. The switching speed—whether to settle to a new frequency or within 2 dB of a new amplitude setting—is a mere 200 ns. Frequency resolution can be specified as fine as 1 Hz, depending on requirement, and typical output power is +10 dBm with ±2 dB output-power flatness across the full frequency range and an operating temperature range of 0 to +50°C.

Of course, switching speed without good spectral purity would introduce false readings in many military systems, so the UFS synthesizers (Fig. 1) are designed to operate with low phase noise, harmonics, and spurious levels. The UFS-18 exhibits low harmonic levels of −50 dBc, with maximum spurious levels of −70 dBc from 0.3 to 18 GHz. The single-sideband (SSB) phase noise is −60 dBc/Hz offset 10 Hz from a 10-GHz carrier, dropping to −90 dBc/Hz offset 100 Hz from the same carrier, −126 dBc/Hz offset 10 kHz from the same carrier, and reaching −140 dBc/Hz offset 10 MHz from a 10-GHz carrier. SSB phase noise in low-noise version is dropping to −147 dBc/Hz offset 10 MHz from the same 10-GHz carrier. A low-noise option further reduces the SSB phase noise floor to a pristine −147 dBc.

The synthesizer is equipped with an internal oven-controlled crystal oscillator (OCXO), which delivers frequency accuracy of 1 PPM. The synthesizer can also phase lock to an external 5- or 10-MHz reference source, assuming the frequency accuracy of that source in the process. The UFS-18 weighs 60 lbs. and measures 5.22 × 16.75 × 22 in. (13.3 × 42.5 × 55.9 cm). It can be programmed remotely by means of 44-b parallel binary-coded-decimal (BCD) commands (the company provides easy-to-use, Windows-based software for ease of programming); GPIB programmability is available as an option on this model as well as other frequency derivatives.

The UFS Series synthesizers are well suited for any applications requiring fast measurement throughput or high-speed frequency/amplitude switching, including radar cross-section measurements, antenna testing, EW LO generation, and wideband surveillance monitoring. They are designed for operating temperatures from 0 to +50°C and can be supplied with a variety of optional modulation formats, including wideband amplitude modulation (AM), wideband frequency modulation (FM), phase modulation, and (10-ns-risetime) pulse modulation. The wideband FM supports modulation bandwidths of DC to 6 MHz in DC mode and 3 kHz to 6 MHz in AC mode. FM deviation can be controlled over a range of ±100 MHz peak-to-peak at rates of 250 MHz/µm. Digital modulation, which can be used to generate digital chirp output signals, is available with an instantaneous bandwidth of 40 MHz. the fast-risetime pulse modulation is available with on/off ratios of 80 dB to 18 GHz. Along with the wide array of modulation possibilities, the UFS frequency synthesizers can be packaged according to a customer's requirements, including in VXi configuration, with a front-panel keypad and display for data entry, and with front-panel SMA RF output connectors.

In addition to the UFS series, the company also offers the WMFS series of module-format synthesizers for military applications from 1 to 23 GHz (in 6-GHz bands), the MFS Series of sources for satellite-communications applications, the DFS series of 1-to-23-GHz (in bands) synthesizer modules for digital radios, and the low-power broadband IBS series of VME synthesizers for commercial and military use from 0.05 to 18.0 GHz. The WMFS series synthesizers, for example, feature output power to +14 dBm with 1-Hz frequency resolution, −70 dBc typical spurious performance, and −95 dBc/Hz phase noise offset 100 kHz from a 10-GHz carrier. Elcom Technologies, 11 Volvo Dr., Rockleigh, NJ 07647; (201) 767-8030, FAX: (201) 767-6266, e-mail: [email protected], Internet:

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