The new RF Signal Generator SG394, with carrier frequencies from DC to 4.050 GHz, support both analog and vector modulation.
The instrument utilize a new RF synthesis technique which provides spur free outputs with low phase noise (-116 dBc/Hz at 1 GHz) and extraordinary frequency resolution (1 μHz at any frequency).
Both analog modulation and vector baseband generators are included as standard features.
The instrument use an ovenized SC-cut oscillator as the standard timebase, providing a 100 fold improvement in the stability (and a 100 fold reduction in the in-close phase noise) compared to instruments which use a TCXO timebase.
OCXO or Rubidium Timebase
The SG390 Series come with a oven-controlled crystal oscillator (OCXO) timebase.
The timebase uses a third-overtone stress-compensated 10 MHz resonator in a thermostatically controlled oven.
The timebase provides very low phase noise and very low aging.
An optional rubidium oscillator (Opt. 04) may be ordered to substantially reduce frequency aging and improve temperature stability.
An external 10 MHz timebase reference may be supplied to the rear-panel timebase input.
Remote operation is supported with GPIB, RS-232 and Ethernet interfaces.
All instrument functions can be controlled and read over any of the interfaces.
Up to nine instrument configurations can be saved in non-volatile memory.
The SG390 Series Signal Generators are based on a new frequency synthesis technique called Rational Approximation Frequency Synthesis (RAFS). RAFS uses small integer divisors in a conventional phase-locked loop (PLL) to synthesize a frequency that would be close to the desired frequency (typically within ±100 ppm) using the nominal PLL reference frequency.
The PLL reference frequency, which is sourced by a voltage controlled crystal oscillator that is phase locked to a dithered direct digital synthesizer, is adjusted so that the PLL generates the exact frequency.
Doing so provides a high phase comparison frequency (typically 25 MHz) yielding low phase noise while moving the PLL reference spurs far from the carrier where they can be easily removed.
The end result is an agile RF source with low phase noise, essentially infinite frequency resolution, without the spurs of fractional-N synthesis or the cost of a YIG oscillator.