Speedy Synthesizer Spans 0.2 To 20.0 GHz

This addition to the QuickSyn line of compact frequency synthesizers brings low-phase-noise performance and fast switching speed to a bandwidth of 200 MHz to 20 GHz.

Impressive for its combination of switching speed and low phase noise, the first compact QuickSyn frequency synthesizer from Phase Matrix, introduced in late 2008, was nonetheless limited to applications through 10 GHz. In response to the needs of broadband coverage for radar and electronic-warfare (EW) applications, the company has released its latest version of the innovative signal source with double the bandwidth of the original model. The newest QuickSyn model operates from 200 MHz to 20 GHz with 100 s switching speed and phase noise of -110 dBc/Hz 10 kHz from the carrier.

The initial model FSW-0010 synthesizer covers 0.5 to 10.0 GHz. The new model FSW-0020 ranges from 0.2 to 20.0 GHz with no frequency multiplication. Both models tune across their frequency ranges with 0.001-Hz resolution. The broadband 20-GHz QuickSyn frequency synthesizer (Fig. 1) employs a fundamental-frequency voltagecontrolled oscillator (VCO) as the tunable oscillator, locked to a lownoise oven-controlled crystal oscillator (OCXO) frequency reference by means of a wide phase-lock-loop (PLL) bandwidth. The synthesizer is based on the company's patented phaserefining technology (see Microwaves & RF, October, 2008, pp. 101-110) to achieve extremely low levels of phase noise even with high-speed frequency switching. Figure 2 shows a plot of phase noise for a 20-GHz carrier signal. The synthesizer exhibits noise of about -115 dBc/Hz offset 10 kHz from the carrier, dropping to about -147 dBc/Hz far from the carrier.

The 20-GHz QuickSyn frequency synthesizer is small even when compared to modular synthesizers, measuring just 5 x 7 x 1 in. and weighing just 2.1 lbs. But it produces at least +13 dBm output power with a power control range of -10 to +13 dBm by means of a built-in attenuator. It operates from a +12-VDC supply and consumes only 20 W power. In terms of spectral purity, the synthesizer has harmonic content of -40 dBc and spurious content of -60 dBc. As shown by Fig. 2, the phase noise is typically -77 dBc/Hz offset 100 Hz from the carrier, typically -106 dBc/Hz offset 1 kHz, and -115 dBc/Hz offset 100 kHz. The synthesizer operates from its internal 10-MHz reference or an external reference source capable of supplying 10 MHz at +5 dBm.

Although this 20-GHz synthesizer is a fraction of the size of a rackmount instrument, it offers many of the same features as larger units. It offers a full complement of modulation capabilities, with built-in amplitude modulation (AM), frequency modulation (FM), phase modulation, and pulse modulation. It can perform sweeps from a starting power level to an ending power level as well as from a start frequency to a stop frequency. It can also tune frequency in a list mode, using a set of user-programmed frequencies for extremely fast frequency switching and settling times.

The synthesizer typically offers leveled output power of 1 dB across its full frequency range, and provides a user with the means to maintain that accuracy over time. Using its built-in attenuator and digitalto-analog converter (DAC), the frequency synthesizer can maintain leveled output power under digital control. It also includes a temperature sensor that provides information needed to calibrate the source's output power as a function of temperature, using a sophisticated frequency and temperature interpolation routine. This same capability allows a user to create a custom power-to-frequency slope to compensate for the effects of connecting cables, filters, and other components in a measurement setup.

The 20-GHz QuickSyn's frequency-tuning calculations and control are orchestrated by a built-in 200-MHz, 32-b reduced-instruction-setcomputing (RISC) microprocessor. The synthesized signal source includes an SPI interface for fullduplex communications to and from a controller with high throughput, as well as a Universal Serial Bus (USB) port for connection to most modern personal computers (PCs). The small source offers the performance and value sought by many commercial designers, and now the bandwidth needed by many military system and component designers.

Phase Matrix, Inc., 109 Bonaventura Dr., San Jose CA 95134; (408) 428- 1000, FAX: (408) 428-1500, Internet: www.phasematrix.com.

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