A Agarwal

Bio: A Agarwal is an academic researcher from Singapore Science Park. The author has contributed to research in topics: Deep reactive-ion etching & Microelectromechanical systems. The author has an hindex of 2, co-authored 2 publications receiving 64 citations.

Low-loss lateral micromachined switches for high frequency applications

Abstract: Two novel lateral metal-contact radio-frequency microelectromechanical system (RF MEMS) switches are reported. These switches are implemented with quasi-finite ground coplanar waveguide (FGCPW) configuration and actuated by applying electrostatic force on a high-aspect-ratio cantilever beam. It is demonstrated that the insertion loss of the switch is less than 0.2 dB up to 15 GHz and the isolation is higher than 20 dB up to 25 GHz. An RF model of the switches is used to analyse the effects of the switch design parameters and RF performance. The optimization of the switch mechanical design is discussed where the threshold voltage can be lower than 25 V. The lateral switches are fabricated by deep reactive ion etching (DRIE) process on a silicon-on-insulator (SOI) wafer with shadow mask technology.

A single-mask substrate transfer technique for the fabrication of high-aspect-ratio micromachined structures

Abstract: In this paper, a single-mask substrate transfer process for the fabrication of high-aspect-ratio (HAR) suspended structures is presented. The HAR silicon structures are fabricated using a deep reactive ion etching (DRIE) technique and then transferred to a glass wafer using silicon/thin film/glass anodic bonding and silicon thinning techniques. The HAR structures are released using self-aligned wet etching of the glass. Two key processes are discussed. One is the silicon/thin film/glass anodic bonding, with special emphasis on the effect of the bonding material on the bonding shear strength. The other is the silicon backside thinning via aqueous solution of potassium hydroxide (KOH). A lateral RF MEMS switch has been fabricated and demonstrates low loss up to 25 GHz. This substrate transfer process has the advantages of high-aspect ratio, low loss and high flexibility.

Integrated circuit design with NEM relays

Abstract: To overcome the energy-efficiency limitations imposed by finite sub-threshold slope in CMOS transistors, this paper explores the design of integrated circuits based on nano-electro-mechanical (NEM) relays. A dynamical Verilog-A model of the NEM relay is described and correlated to device measurements. Using this model we explore NEM relay design strategies for digital logic and I/O that can significantly improve the energy efficiency of the whole VLSI system. By exploiting the low effective threshold voltage and zero leakage achievable with these relays, we show that NEM relay-based adders can achieve an order of magnitude or more improvement in energy efficiency over CMOS adders with ns-range delays and with no area penalty. By applying parallelism, this improvement in energy-efficiency can be achieved at higher throughputs as well, at the cost of increased area. Similar improvements in high-speed I/O energy are also predicted by making use of the relays to implement highly energy-efficient digital-to-analog and analog-to-digital converters.

Design, Optimization, and Scaling of MEM Relays for Ultra-Low-Power Digital Logic

Abstract: Microelectromechanical relays have recently been proposed for ultra-low-power digital logic because their nearly ideal switching behavior can potentially enable reductions in supply voltage (Vdd) and, hence, energy per operation beyond the limits of MOSFETs. Using a calibrated analytical model, a sensitivity-based energy-delay optimization approach is developed in order to establish simple relay design guidelines. It is found that, at the optimal design point, every 2 X energy increase can be traded off for a ~1.5x reduction in relay delay. A contact-gap-to-actuation-gap thickness ratio of 0.7-0.8 is shown to result in the most energy-efficient relay operation, implying that pull-in operation is preferred for an energy-efficient relay design. Based on the analytical model and design guidelines, a scaling theory for relays is presented. A scaled relay technology is projected to provide >; 10 X energy savings over an equivalent MOSFET technology, for circuits operating at clock frequencies up to ~100 MHz.

Design, fabrication and RF performances of two different types of piezoelectrically actuated Ohmic MEMS switches

Abstract: In this paper, we have proposed, fabricated and characterized piezoelectrically actuated RF MEMS (radio-frequency micro-electro-mechanical system) switches. They have been designed to operate at a low operation voltage for advanced mobile/wireless handset applications. The proposed switches are largely composed of piezoelectric cantilever actuators with an Au contact electrode and CPW (coplanar wave) transmission lines suspended over the substrate. Two different types of RF MEMS switches have been suggested to find the better geometry. One has the structure of one single piezoelectric cantilever and a contact electrode attached to its edge with three hinges (type-A), and the other contains four piezoelectric cantilevers that are symmetrically combined through each hinge to support a centered contact electrode (type-B). The two different fabricated (type-A and type-B) RF MEMS switches have insertion losses of −0.22 and −0.23 dB at an operation voltage of 2.5 V and a frequency of 2 GHz, respectively. Although the difference in insertion loss is trivial, there exist different dependences of insertion loss on applied voltage between them. The insertion losses of type-A switches are changed with varying operation voltage because the touching area between the contact electrode and the signal transmission lines is variable. Meanwhile, the type-B switches show nearly constant insertion losses regardless of operation voltage. The type-A and type-B switches have isolation values of −40.8 and −42.5 dB at a frequency of 2 GHz, respectively.