Filter-less frequency-doubling microwave signal generator with tunable phase shift

•A filter-less architecture for frequency-doubling microwave signal generator with tunable phase shift is proposed.•Wide bandwidth and tunable phase shift are obtained simultaneously for the generation of microwave signal.•The tunable phase shift is controlled simply by DC regulated power supply.•The system possesses good frequency tunability and multi-wavelength compatibility.•High frequency beyond the operation bandwidth of the modulator and the electrical 90° hybrid can be achieved

A prototype for frequency-doubling microwave signal generator with tunable phase shift based on a filter-less architecture is proposed and analyzed. In the proposal, one dual parallel polarization modulator is used as the key component to generate two ±1st order sidebands along the orthogonal polarization directions with suppressed carrier. Then the polarization states of the two sidebands are aligned with the principal axes of an electro-optical phase modulator (EOPM). Tunable phase shift is implemented by controlling the direct current voltage applied to the EOPM. Without using any filters or wavelength-dependent components, the system possesses good frequency tunability and it can be applied to multi-wavelength operation. Taking advantage of the ability of frequency multiplication, the frequency tuning range can be wider than the operation bandwidth of the modulator. By theoretical analyses and simulated verifications, a frequency-doubling microwave signal ranging from 22 to 40 GHz with full range phase shift is achieved.