Wideband, low noise and low spurious agile direct frequency synthesis based on combination of SAW oscillator and high speed DAC

In this article is demonstrated that direct digital synthesizer using low phase noise local oscillator and high speed DAC allows reaching simultaneously high purity and high agility synthesis. A multiplied-frequency OCSO (Oven Controlled SAW Oscillator) is used to provide the clock to the DAC and also to up-convert the output frequency DAC in any microwave frequency band of interest. Within our experiments operating in high-frequency band, we obtain a 400 MHz bandwidth up-converted direct frequency synthesis, showing a high Spurious Free Dynamic Range (SFDR) and a low phase noise level.