Journal Article

Improvement of performance of optically controlled microstrip phase shifters

Safwat, A.M.E., El Khaldi, M., Vilcot, A., Podevin, F., Exshaw, O.

2007

Overview

Two optically controlled phase shifters are proposed. The first structure is based on the microstrip ring resonator inserted between two gaps. Phase-shifting is performed by optically controlling the gaps capacitance. The structure has shown excellent characteristics, however the rejection rate is high. To minimise the reflected power, the second phase shifter, which is based on the rat race coupler, is proposed. In this case, the phase-shifting is performed by adding extra lengths to two gaps, judiciously placed along the microwave ports. The gaps act as short-circuits under sufficient illumination conditions. At 10 GHz, the structure provides a continuous variation of Δφ(S^sub 21^) between 0 and 90°, with Δ|S^sub 21^| less than 5 dB. On a 500 MHz band around 10 GHz, the phase variation is less than 5%. |S^sub 11^| keeps < -20 dB within the experimental bandwidth 8.9-10.7 GHz. Both structures were fabricated on high-resistivity silicon substrate and the experimental results confirm the three-dimensional electromagnetic simulations.

• Publisher: Institution of Engineering and Technology,The Institution of Engineering & Technology
• Subject: Applied sciences / Circuit properties / Circuits of signal characteristics conditioning (including delay circuits) / Electric, optical and optoelectronic circuits / Electronic circuits / Electronics / Exact sciences and technology / Illumination / Microwave antennas / Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits / Microwaves / Noise levels / Oscillators, resonators, synthetizers / Phase shifters / Silicon substrates / Simulation / Three dimensional