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.