Xinyi Li

A 4-bit switched-line phase shifter based on MEMS switches

This paper presented a 4-bit switched-line phase shifter based on the metal-contact SPDT RF MEMS switches. The phase shift module was fabricated on a 20mil RO4350 substrate and mounted with its driver module on an Aluminum platform. This electrically tunable phase shifter is suitable for taking place of mechanical phase shifters used in base station. Measurements indicated a maximum phase shift of 75 degree with a step of 5 degree, a maximum insertion loss of 0.89dB and a minimum return loss of 13.4dB at 2.7GHz. The phase accuracy is within 2 degree at 2.7 GHz.

A 1.7–2.7-GHz 4-bit Phase shifter based on packaged RF MEMS switches

This study presents a 4-bit phase shifter with a maximum phase shift degree of 75° based on packaged metal-contact single-pole double-throw (SPDT) radio frequency microelectromechanical system (RF MEMS) switches mounted on a 20 mil RO4350 substrate and assembled with its driver module on a 4-layer printed circuit board (PCB) board. Electric length of 10° and characteristic impedance of 61.7 Ω are selected for T-stub matching. Standard PCB processing makes it easy to develop and suitable for taking place of mechanical tilt employed in recent base station. Measurements indicate a maximum insertion loss of 1.37 dB at 2.7 GHz and a minimum return loss of 11.71 dB. The phase accuracy is within 1.75° at 2.7 GHz.

Influence of coupling between Rayleigh and SH SAWs on rotated Y-cut LiNbO 3 to their electromechanical coupling factor

Suppression of the SH-SAW response is mandatory to design TC SAW devices on θ degree rotated Y-cut LiNbO<inf>3</inf>. However, it is not easy because K² for SH SAW changes rapidly with θ, and its optimal value in terms of the SH-SAW suppression is dependent on electrode and SiO<inf>2</inf> thicknesses. The authors found that the optimal θ always locates close to θ where difference in velocities of two SAWs is minimum. This suggested that their coupling is responsible for variation of their K².