Remarkably, the ERASynth from ERA Instruments uses a multi-loop PLL architecture to provide continuous frequency coverage from 250 kHz to 15 GHz in 1 Hz steps. That’s in contrast with single-loop fractional PLLs with integrated VCOs which, although great for generating RF signals with fine frequency resolution, are often plagued by high phase noise floors and an undergrowth of spurious artifacts.
ERAsynth is an open source, crowd-funded project — now available on Crowd Supply — aiming to make multi-GHz RF signal synthesis accessible to everyone.

The crux of ERAsynth is to make the reference tunable and keep the main PLL in integer mode at all times. The end result, the creator claim, is a low-cost, low-SWaP (size, weight and power) and high-performance RF synthesizer with impressive specs. Phase noise, for example, is –125 dBc/Hz at 1 GHz, and the 10 kHz offset exceeds even some of the premium bench-top signal generators.

Measuring just 10 x 14.5 x 2 cm, ERASynth is equipped with a low-power ±25 ppb OCXO for ultra-stable operation.

Image: Crowdsupply / ERA Instruments