Photonic control technology for Phased Arrays

Phased arrays radars can expect considerable improvements with RF photonics. Current TR modules use numerous MMIC chips, ferrite circulators and phase shifters and quasi-optical true-time-delay (TTD). Transmission power distribution and synchronization across multiple RF interfaces can be improved. Large scale integration could address the problem of interconnecting boards with GHZ RF outputs but currently is not possible. Such integration with optical control will be a key enabling technology. ODIS proposes a monolithic IC solution based upon novel optoelectronic (OE) thryistor circuit design. Thyristor/HFET circuits implement a novel power amplifier using a gated OE oscillator driving a Class E output. The receive channel is implemented with an photonic link based upon linear phase modulation and coherent detection which achieves an SFDR of -92dB and SNR of -149dB. The photonic receive link also implements narrow channel microwave filtering in the optical domain. The photonic technology also enables novel AD architectures for the back end conversion or for direct digitization after the LNA. The photonic insertion is in the form of monolithic integrated circuits and the fabrication technology includes high temperature (850C) processing which pre-qualifies it for the mil-spec environment. Elimination of oxides results in rad-hard circuits. The in-plane photonics simplifies the package.