Department of Electrical Engineering

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IIT Jodhpur

In this paper, TiN film has been deposited and optimized at room temperature for high power radio-frequency microelectromechanical system (RF-MEMS) applications. Being hard, titanium nitride is used in the contact area. The contact material should have low resistance and high hardness. TiN thin films were deposited by DC magnetron reactive sputtering using a four inch high purity titanium target in a nitrogen (N2) environment. X-ray diffraction (XRD) analysis is used to confirm crystal structure and purity of TiN film. The effect of various N2 pressure on resistivity and hardness of TiN thin film is investigated. The resistivity of the film decreases and hardness increases with N2 pressure. © 2019, The Minerals, Metals & Materials Society.

World University root node

Journal of Electronic Materials

Optimization of Titanium Nitride Film for High Power RF MEMS Applications

Fifth generation (5G) communication system enables the pathway for a higher data transfer rate. The frequency bands used for 5G communication system are distributed from lower frequency range (600 MHz) to a higher frequency range (60 GHz). So it is necessary that a single switch should be able to cover the complete range of 5G frequency bands. The ohmic radio frequency-micro electromechanical system (RF-MEMS) switch has offered high isolation at lower frequencies (> 40 dB up to 2.5 GHz). However, 5G requires a higher frequency range which is covered by capacitive switch. The capacitive switch has limitations of limited bandwidth and large size. In this paper, a hybrid technique is used for the designing of a compact, high isolation and the enhanced bandwidth SPDT RF MEMS switch for 5G applications. The size of the proposed switch is half from the conventional capacitive RF MEMS switch and offer greater than 40 dB isolation over a wide frequency range (> 40 dB over 22.10 GHz bandwidth) with less than 0.30 dB insertion loss over the entire band. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.

Microsystem Technologies

Compact high isolation and improved bandwidth hybrid RF MEMS SPDT switch for 5G applications

This paper presents the design and fabrication of MEMS based electro-thermally actuated square membrane/plate with gold and silicon dioxide bimorph beams. The main objective of this work is to generate a suspended bimorph structure for tunable cavity filters and resonators. A surface micromachining process has been employed in which bimorph structure is suspended by removing underneath sacrificial layer of photoresist through dry and wet etching. A major fabrication challenge is the release of square plate bimorph structure. Increase in temperature during subsequent processing steps cause excessive baking of photoresist. The possible reason of the hard sacrificial resist is baking beyond its thermal budget. Active layer of silicon dioxide utilized as a reinforcing layer during release. In the proposed process, over etched silicon dioxide and presence of sacrificial resist leads to process failure. Controlled thermal budget of sacrificial resist is essential for fully suspended structure. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.

Fabrication of electro-thermally driven tunable plate with Au/SiO2 bimorph beams

Resonant inductive power transfer (RIPT) is gaining in popularity for wireless charging applications of future electric transportation. A fundamental impediment to the efficient operation of an RIPT system is the existence of bifurcation phenomenon in a doubly tuned circuit. Bifurcation can be avoided by either selecting complicated control strategies or by proper design strategies. Many control strategies have been presented in the literature for avoiding bifurcation. However, systematic design strategies for avoiding bifurcation are still unknown. This paper presents a simplified, and easy to follow set of design guidelines for series-series compensated RIPT (SS-RIPT) systems. The design guidelines avoid bifurcation by calculating the parameters for a given load profile in a systematic and easy to follow approach. Following the design guidelines, a 3.6-kW setup has been fabricated as an example and verified using a finite element analysis as well as experimental testing. Selection of a resonant frequency and output voltage for 3.6 kW was influenced by the availability of testing equipment available in the lab. However, the design guidelines are generalized, and by following it, an SS-RIPT system of any frequency and output voltage rating, applicable for EV charging, can be designed. © 1982-2012 IEEE.

IEEE Transactions on Industrial Electronics

Design guidelines to avoid bifurcation in a series-series compensated inductive power transfer system

Bio-signals such as electroencephalogram (EEG) contain low activity regions often called B-noise and high activity regions called active potentials. The high activity regions are more important as compared to their counterpart. In addition, the signals are considerably sparse in the low activity regions. Thus a full n-bit conversion of low activity samples into digital domain increases readout power and reduces data acquisition rate of analog to digital converter (ADC). To alleviate these problems, a reconfigurable cyclic ADC is presented in this paper. Input range and conversion cycles of the proposed ADC are varied according to the samples of the neural signal. The high activity region samples are resolved using conventional n-bits, however, the low activity region is resolved using less number of bits. This saves readout power and also reduces the digital data content. The proposed ADC is designed and fabricated in UMC 180 nm CMOS technology. The ADC operates at a sampling rate of 200 kS/s and consumes 61.8 μW of power. The chip occupies an area of 0.031 mm2. Using reconfiguration, the power saving of 28.6% is achieved compared to the conventional n-bit full conversion. © 2019 IEEE.

Department of Computer Science & Engineering

BioCAS 2019 - Biomedical Circuits and Systems Conference, Proceedings

A reconfigurable cyclic ADC for biomedical applications

This paper presents the timing error and power supply induced jitter (PSIJ) analyses of an inverter based high-speed comparator, including the design of common-mode body biasing feedback circuitry. Both the main circuit and the supporting circuitry have been designed and implemented in a standard 28 nm CMOS technology with power supply of 0.9 V. The closed-form transfer function of the comparator including biasing circuitry, used in PSIJ analysis, is derived using symbolic admittance method. The mathematical model shows an agreement with the simulation and exhibits 7.4% of mean percentage error (MPE). © 2019 IEEE

Proceedings - IEEE International Symposium on Circuits and Systems

Analysis of timing error due to supply and substrate noise in an inverter based high-speed comparator

In this paper, we consider a class of denial-of-service (DoS) attacks, which aims at overloading the communication channel. On top of the security issue, continuous or periodic transmission of information within feedback loop is necessary for the effective control and stabilization of the system. In addition, uncertainty - originating from variation of parameters or unmodeled system dynamics - plays a key role in the system's stability. To address these three critical factors, we solve the joint control and security problem for an uncertain discrete-time Networked Control System (NCS) subject to limited availability of the shared communication channel. An event-triggered-based control and communication strategy is adopted to reduce bandwidth consumption. To tackle the uncertainty in the system dynamics, a robust control law is derived using an optimal control approach based on a virtual nominal dynamics associated with a quadratic cost-functional. The conditions for closed-loop stability and aperiodic transmission rule of feedback information are derived using the discrete-time Input-to-State Stability theory. We show that the proposed control approach withstands a general class of DoS attacks, and the stability analysis rests upon the characteristics of the attack signal. The results are illustrated and validated numerically with a classical NCS batch reactor system. © 2019 IEEE.

Proceedings of the IEEE Conference on Decision and Control

Robust Stabilization of Resource Limited Networked Control Systems under Denial-of-Service Attack

The recently developed IEEE 802.11ad (WiGig) standard offers multi-Gbps connectivity for consumer wireless local area networks and operates in the millimeter wave frequency band (around 60 GHz). It supports two different contention-based channel access mechanisms, namely distributed coordination function, which offers fair service for every station, and the enhanced distributed channel Access (EDCA) for offering service differentiation among the stations. In this paper, we study the throughput performance of the IEEE 802.11ad EDCA mechanism under saturated traffic conditions using both analytical and simulation models. A novel five-dimensional Markov chain developed is used for analytically modeling the throughput behavior of the IEEE 802.11ad EDCA in the presence of virtual antenna sectors, high-gain directional beamforming, and presence of contention and contention-free access periods. Using this developed analytical model, the effect of the number of sectors, number of stations, arbitration inter-frame space, packet length, and minimum contention window size on the throughput of the four different access or service categories present in the EDCA under saturated traffic conditions, is investigated. When compared with the simulation outcomes, the proposed analytical model accurately analyzes the network performance by achieving less than 4% error. © 1967-2012 IEEE.

IEEE Transactions on Vehicular Technology

Saturated throughput analysis of IEEE 802.11ad EDCA for High Data Rate 5G-IoT Applications

The primary focus of this paper is to discuss the modeling of jitter caused by power supply noise (PSN), named power supply induced jitter (PSIJ). A holistic discussion is presented from the basics of power delivery networks to PSN and eventually to the modeling of PSIJ. The in-depth details and a review of several methodologies available in the literature for the estimation of PSIJ are presented. © 2011-2012 IEEE.

IEEE Transactions on Components, Packaging and Manufacturing Technology

A review on power supply induced jitter

In this paper, a novel mode decoupling technique of a SIW dual mode square resonator is presented. It is then utilized to design a self diplexing radiator. A single corner cut square cavity with a triangular ring slot on top is used for dual mode excitation and mode decoupling. Both the electric and magnetic mode couplings are used simultaneously to improve the port isolation. Once the single square cavity is optimized for good port isolation, two extra TE110 mode cavities are further added to improve the isolation. Finally, 37 dB port isolation is achieved. The measured gains are 4.45 dBi and 4.20 dBi at 10.5 GHz and 11.7 GHz respectively. The proposed design can be used in a transceiver system without any circulator, switch or additional bandpass filter. © 2019 IEEE.