Zongsheng Lai

Bio: Zongsheng Lai is an academic researcher from East China Normal University. The author has contributed to research in topics: RF switch & Low voltage. The author has an hindex of 3, co-authored 4 publications receiving 85 citations.

Preparing of a high speed bistable electromagnetic RF MEMS switch

Abstract: A radio-frequency micro-electro-mechanical systems (RF MEMS) switch with bistable states based on electromagnetic actuation is presented The switch has two stable positions due to the adoption of the permanent magnets, which will lead to a lower power consumption of the device With electromagnetic actuation arising from the planar coils, the cantilever beam can switch from one stable position to the other The structure sizes of the switch are simulated by the finite element software of the ANSYS 70 The device with a size of 20 mm × 22 mm is fabricated by UV-LIGA technology A current pulse with an amplitude of 50 mA is needed for the fabricated switches’ switching between two stable states that is in good agreement with the simulation, and the switching time is only approximately 20 μs The insertion loss is −011 dB, and the isolation is −43 dB at 3 GHz

Study on low voltage actuated MEMS rf capacitive switches

Abstract: We report the study on the MEMS rf switches with low actuated voltage. The switch structure has been optimized by the calculation on the dependence of actuated voltage on the Young’s modulus of membrane materials and geometrical sizes. Compared with gold material, AlSi0.04 is a good movable film material having lower actuated voltage (5 V). The switches array is made on the coplanar waveguide (CPW) transmission lines, which were fabricated on quartz, high resistivity (>2 kΩ cm) silicon and porous silicon substrates respectively. The pull-in voltage of the variable capacitor was below 20 V. Furthermore, the 21 bridges MEMS switch array had 372°/3.5 mm phase shift operating at 35 GHz. The chip is compacted into a size of 3.5 mm ×0.5 mm .

A novel integrated 3-D DMOS magnetic vector sensor based on BCD technology

Abstract: A new integrated three-dimensional DMOS magnetic vector sensor has been proposed in this paper. The basic sensor structure is obtained by combining a 1-D split-drain lateral DMOS (LDMOS), which is sensitive to the B z , with a 2-D vertical DMOS (VDMOS), which is sensitive to B x and B y . The spatial resolution of the sensor is 10 × 16 × 32.5 μm 3 if only one split-drain pair was used. The sensor shows good linearity for fields lower than 0.5 T and the measured temperature coefficient of the sensitivity is less than 0.2%/ °C. The relative sensitivity S RY is higher than 6% T −1 . With the BCD technology, bipolar, CMOS and DMOS devices can be integrated with the DMOS magnetic sensor on the same chip. So it will make an optimum and flexible design of the peripheral circuits which would have excellent performance.

Laminated Photoresist Sacrificial Layer Technology for MEMS

Abstract: Laminated photoresist sacrificial layer process has been developed to fabricate suspended micro-structures. Different problems related to the process such as air bubble, crack, crinkle, black floccule and adhesion are discussed and their solutions are proposed. The perfect suspended structure is successfully achieved utilizing wet release technology with in-sequence-removal method for the e tching of the laminated photoresist and in-sequence-displacement method forthe release of cantilever beam. The distance is about 10 μm from the substrate to the cantilever beam with a length of 1400 μm, a thickness of 6 μm and a width of 40 μm.

Nanoscale memory cell based on a nanoelectromechanical switched capacitor.

Abstract: The demand for increased information storage densities has pushed silicon technology to its limits and led to a focus on research on novel materials and device structures, such as magnetoresistive random access memory and carbon nanotube field-effect transistors, for ultra-large-scale integrated memory. Electromechanical devices are suitable for memory applications because of their excellent 'ON-OFF' ratios and fast switching characteristics, but they involve larger cells and more complex fabrication processes than silicon-based arrangements. Nanoelectromechanical devices based on carbon nanotubes have been reported previously, but it is still not possible to control the number and spatial location of nanotubes over large areas with the precision needed for the production of integrated circuits. Here we report a novel nanoelectromechanical switched capacitor structure based on vertically aligned multiwalled carbon nanotubes in which the mechanical movement of a nanotube relative to a carbon nanotube based capacitor defines 'ON' and 'OFF' states. The carbon nanotubes are grown with controlled dimensions at pre-defined locations on a silicon substrate in a process that could be made compatible with existing silicon technology, and the vertical orientation allows for a significant decrease in cell area over conventional devices. We have written data to the structure and it should be possible to read data with standard dynamic random access memory sensing circuitry. Simulations suggest that the use of high-k dielectrics in the capacitors will increase the capacitance to the levels needed for dynamic random access memory applications.

Dual-Beam Actuation of Piezoelectric AlN RF MEMS Switches Monolithically Integrated with AlN Contour-Mode Resonators

Abstract: This work reports on piezoelectric aluminum nitride (AlN) based dual-beam RF MEMS switches that have been monolithically integrated with AlN contour-mode resonators. The dual-beam switch design presented in this paper intrinsically compensates for the residual stress in the deposited films, requires a low actuation voltage (5 to 20 V) and facilitates active pull-off to open the switch and exhibits fast switching times (1 to 2 µs). This work also presents the combined response (cascaded S parameters) of a resonator and a switch that were co-fabricated on the same substrate. The response shows that the resonator can be effectively turned on and off by the switch. A post-CMOS compatible process was used for the co-fabrication of both the switches and the resonators. The single-chip RF solution presented constitutes an unprecedented step forward towards the realization of compact, low-loss and integrated multi-frequency RF front-ends.