This paper presents a high reliable direct-contact electrostatic RF MEMS switch. To enhance the reliability, the contact structure of the switch is designed into a circular shape, and the bottom contact surface is covered by a hard metal Pt layer. Besides, a high resistance silicon cap is used for hermetic packaging of the switch structure. By theoretical calculation and FEM simulation, parameters of the switch structure as well as its packaging are co-designed and optimized. During fabrication, the circular contact structure is formed by a three-step etching process; and after fabrication, the silicon hermetic packaging is realized by epoxy bonding and multi-step dicing process. The measured insertion loss and isolation of the switch with package is -0.41@ 20GHz, and -20.9@20GHz. Because of the optimization design, the RF performance of the switch keeps almost unchanged before and after packaging. The measured driving voltage is 50~60V, and the ON/OFF switching time is 25μs/5μs. The lifetime test shows that the switch passes the 2.6 billion times hot switching at the working power of 25 dBm. Finally, the switch also shows good performances in package leak rate test.

At the broken phase of a parity-time (PT)-symmetric dimer where the coupling is weak, the eigenfrequencies are complex conjugate pairs with non-vanishing real parts, leading to oscillation magnitudes with an exponentially growing mode and an exponentially decaying mode. If the large oscillation magnitudes are clamped due to the nonlinear gain of the PT-symmetric dimer, the exponentially growing mode eventually enters the stable oscillations. It was recently demonstrated that such a phenomenon can be utilized for non-reciprocal transmission. The distortion induced by nonlinearity is critical for the non-reciprocal transmission. Here, we experimentally explore the nonlinear distortion in PT-symmetric inductor–capacitor resonators by utilizing discrete components on a printed circuit board. It demonstrates that the IIP3 (the output-referred third-order intercept point) can achieve as high as 38.7 dBm at the frequency of 14.5 MHz corresponding to the maximum forward transmission. The noise figure of the system is measured to be about 11.25 dB.

Non-reciprocal devices that allow a signal to be transmitted only in one direction are important for full-duplex communications. Due to the requirements of miniaturized systems, there has been an increase interest in non-magnetic non-reciprocal devices in recent years. Based on parity-time (PT) symmetric inductors-capacitors (LC) resonators, this paper has proposed non-reciprocal transmission configurations by PT-symmetry breaking. In the configuration, the coupled capacitance between the two coupled LC resonators can be adjusted so that the transmission frequency is tunable. At the same time, the resonant frequency and transmission frequency have been discriminated to optimize the non-reciprocal transmission. The configuration has been implemented by utilizing discrete components on a printed circuit board (PCB). It demonstrates that the center operation frequency of 14.05 MHz with the bandwidth 4 MHz, the insertion loss 0.32 dB, and the isolation 11 dB is adjusted to the center operation frequency of 14.95 MHz with the bandwidth 4.6 MHz, the insertion loss 0.716 dB, and the isolation 14.5 dB.

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