Wideband and low phase noise up-converted direct frequency synthesis using high frequency DAC and oscillator

This article demonstrates that up-converted direct frequency synthesizer using low phase noise local oscillator and high speed DAC (Digital to Analog Converter) allows reaching simultaneously high spectral purity and wide frequency agility. A multiplied-frequency OCSO (Oven Controlled SAW Oscillator) or an OEO (Opto-Electronic 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 S or×frequency band, we obtain more than 500 MHz bandwidth, showing a high Spurious Free Dynamic Range (SFDR) about 70 to 80 dBc and a very low phase noise level (lower than −140 dBc/Hz).