Low-Noise Synthesizers Switch In Microseconds

Sept. 1, 2003
This series of instrument-grade frequency synthesizers offer list-mode frequency switching and low noise at frequencies from 10 MHz to 40 GHz.

High-throughput measurements, such as antenna testing and RF integrated-circuit (RF IC) characterization, call for a fast-switching frequency synthesizer. Until recently, instrument synthesizers with microsecond switching speed came with hefty price tags. But the new 2400 Series of microwave frequency synthesizers from Giga-tronics (San Ramon, CA) offer fast frequency switching and low phase noise without breaking the bank. Several instrument configurations are available covering 10 MHz to 8 GHz, 10 MHz to 20 GHz, and 10 MHz to 40 GHz.

The 2400 Series of frequency synthesizers (see figure) includes models with and without front-panel display screens and keypads. Model 2408L, for example, operates from 10 MHz to 8 GHz, while models 2420L and 2440L operate from 10 MHz to 20 GHz and 10 MHz to 40 GHz, respectively. The same numbers with "AL" suffix (for example, model 2408AL) are configured with a blank front panel, rear-panel RF output jack, GPIB interface, and optimized for automatic-test-equipment (ATE) environments.

Standard models offer 1-kHz frequency resolution; an option shaves tuning resolution to a fine 0.1 Hz. The synthesizers feature generous output power, with +15 dBm output power to 20 GHz and +9 dBm output power to 40 GHz. At an output level of +10 dBm, the output power remains flat within ±1.0 dB to 20 GHz and ±1.2 dB to 40 GHz.

Although the frequency synthesizers can be programmed to sweep through frequencies and power levels is about 10 ms per point, it is in List mode that they show their true speed. By downloading a list of frequencies and power levels via GPIB or with an RS-232C or USB connection to a personal computer (PC) running the supplied WaveMaker software, the 2400 Series synthesizers can settle to a new frequency in less than 400 µs and settle to a new power level is less than 200 µs. The Windows-based WaveMaker software includes an autoprogramming mode and includes a command-line interpreter.

The synthesizers maintain spectrally pure output signals, with phase noise of −91 dBc/Hz offset 100 Hz from a 2-GHz carrier and −117 dBc/Hz offset 100 kHz from a 2-GHz carrier. At 10 GHz, the phase noise is −79 dBc/Hz offset 100 Hz and −105 dBc/Hz offset 100 kHz. P&A: $17,000 and up; 6 wks. Giga-tronics, Inc., 4650 Norris Canyon Rd., San Ramon, CA 94583; (925) 328-4650, FAX: (925) 328-4700, e-mail: [email protected], Internet: www.gigatronics.com.