Design and technology is an inspiring, rigorous and practical subject. Using creativity and imagination, pupils design and make products that solve real and relevant problems within a variety of contexts, considering their own and others’ needs, wants and values. They acquire a broad range of subject knowledge and draw on disciplines such as mathematics, science, engineering, computing and art. Pupils learn how to take risks, becoming resourceful, innovative, enterprising and capable citizens. Through the evaluation of past and present design and technology, they develop a critical understanding of its impact on daily life and the wider world. High-quality design and technology education makes an essential contribution to the creativity, culture, wealth and well-being of the nation.

What is Design and Technology

Design and Fabrication

This paper presents a low insertion loss capacitive shunt RF-MEMS switch. In the presented design, float metal concept is utilized to reduce the capacitance in up-state of the device. Float metal switch shows an insertion loss <0.11 dB, a return loss below 26.27 dB up to 25 GHz as compared to 0.81 dB insertion, 8.67 dB return loss for the conventional switch without float metal. OFF state response is same for the both devices. Further pull-in voltage of 12.75 V and switching time of 69.62 µs have been observed in case of the conventional switch whereas device with float metal have 11.75 V and 56.41 µs. Improvement of around 2.5 times in bandwidth and 4 times in input power has been observed without self actuation, hold down problem. The designed switch can be useful at device and sub-system level for multi-band applications.

Design and investigation of a low insertion loss, broadband, enhanced self and hold down power RF-MEMS switch

This paper presents design and simulation of uniform structured RF MEMS capacitive shunt switch using FEM tool and HFSS software. The switches with different shaped meanders and perforations which result in less spring constant, less pull-in voltage, high isolation loss, high switching speed and low insertion loss have been designed. From the simulated results it is observed that the rectangular perforations gives the better results, when compared with square and cylindrical shaped perforations. Comparative study is done for zigzag, plus and three square shaped meander along with rectangular perforations on each structure. When the gap between the dielectric and the movable beam is 0.8 µm, the up state capacitance for HfO2 is 4.06fF and for Si3N4 is 3.80fF. The downstate capacitance for HfO2, Si3N4 is 49fF, 26.9fF respectively. The capacitance ratio is 120.6. Poly-tetra-fluoro-ethylene material is given for the movable beam whose young’s modulus is 0.4 GPa and the spring constant is calculated theoretically for each structure; by using this the pull in voltage and the settling time are calculated. Step switch with three square Meander has switching time 10.25 µs, pull in voltage as 2.45 V. By using HFSS 3-D electromagnetic model we observed the return loss (S11) is less than −60 dB, the insertion loss is less than −0.07 dB in the range of 1–40 GHz frequency and switch isolation (S21) is −61 dB at 28 GHz frequency.

Design and performance analysis of uniform meander structured RF MEMS capacitive shunt switch along with perforations

In this paper, we have developed an electrostatic driven capacitive RF MEMS switch. The actuation voltage is applied to the actuation electrodes, and the DC voltage is isolated from the signal line and RF signals. Actuation area and capacitance area are separated. Thanks to this structure, both low actuation voltage and low up-state capacitance are achieved. The switch can be integrated in RF systems without additional circuits to isolate the DC voltage, so the system is simplified. The proposed switch is fabricated and tested. The insertion loss and isolation of the fabricated switch are 0.29 dB and 20.5 dB at 35 GHz, respectively. The actuation voltage is 18.3 V.

Design and fabrication of a low insertion loss capacitive RF MEMS switch with novel micro-structures for actuation

This paper presents a new type of capacitive shunt RF-MEMS switch. In the proposed design, float metal concept has been utilized to make the asymmetric structure on either side of the transmission line to implement the switch. This novel structure is used to inductively tune the isolation in C, X and Ku bands. Isolation peaks of 42.63, 44.22 and 47.75 dB has been observed at 7.2, 8.8 and 16.5 GHz when left, right or both cantilevers are electro-statically actuated in the down-state respectively, whereas conventional switch has peak only in X-band. Switch shows an insertion loss better than 0.10 dB, a return loss below 23.93 dB up to 25 GHz as compared to 0.90 dB insertion loss and 8.02 dB of return loss in case of conventional device. Further, improvement of around 5 times in bandwidth, 50 % in the pull-in voltage and 16.7 % in device area have also been observed. The designed switch can be useful at device and sub-system level for the future multi-band communication applications.

Performance improvement of RF-MEMS capacitive switch via asymmetric structure design

A novel design for low insertion loss, multi-band RF-MEMS switch with low pull-in voltage

A novel capacitive RF-MEMS switch for multi-frequency operation

This paper presents a novel, highly compact capacitive shunt RF MEMS switch. In the presented configuration interdigitation of signal lines with actuation electrodes is considered. The compactness has been achieved further by incorporating HfO2 a high -k dielectric material in place of traditionally used SiO2. The capacitive overlap area reduces by 70% , leading to the overall reduction of about 15% in the switch size. Switch with HfO2 optimized for X band shows -56.78 dB isolation and 0.058 dB insertion loss at 10 GHz as compared to the -40.8 dB isolation, -0.1 dB insertion loss for the switch with SiO2. Significant improvement in switching time is also observed. Pull-in voltage of 5.6V is obtained at a gap of 1um between bridge and transmission line. The compact switch can be useful for the future communication applications.

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Mahesh Angira

Papers

Design and investigation of a low insertion loss, broadband, enhanced self and hold down power RF-MEMS switch

Performance improvement of RF-MEMS capacitive switch via asymmetric structure design

A novel design for low insertion loss, multi-band RF-MEMS switch with low pull-in voltage

A novel capacitive RF-MEMS switch for multi-frequency operation

On the investigation of an interdigitated, high capacitance ratio shunt RF-MEMS switch for X- band applications