Gallium nitride (GaN) is a compound semiconductor that has tremendous potential to facilitate economic growth in a semiconductor industry that is silicon-based and currently faced with diminishing returns of performance versus cost of investment. At a material level, its high electric field strength and electron mobility have already shown tremendous potential for high frequency communications and photonic applications. Advances in growth on commercially viable large area substrates are now at the point where power conversion applications of GaN are at the cusp of commercialisation. The future for building on the work described here in ways driven by specific challenges emerging from entirely new markets and applications is very exciting. This collection of GaN technology developments is therefore not itself a road map but a valuable collection of global state-of-the-art GaN research that will inform the next phase of the technology as market driven requirements evolve. First generation production devices are igniting large new markets and applications that can only be achieved using the advantages of higher speed, low specific resistivity and low saturation switching transistors. Major investments are being made by industrial companies in a wide variety of markets exploring the use of the technology in new circuit topologies, packaging solutions and system architectures that are required to achieve and optimise the system advantages offered by GaN transistors. It is this momentum that will drive priorities for the next stages of device research gathered here.

This article presents a coplanar waveguide fed global system for mobile communications band integrated ultra wide band (UWB) multiple input multiple output (MIMO) antenna with single and dual notch band characteristics. The novelty of the antenna lies in its design as all the unit cells of the proposed UWB MIMO antenna structure are orthogonal to each other therefore the additional isolation elements responsible for achieving high isolation are not required consequently making proposed antenna design simple and easy to fabricate. In this context, 2 MIMO systems have been designed. The first MIMO system is consisting of a dual port antenna whereas the second MIMO system is a printed quad port antenna; further single and dual notch band are achieved in the proposed multi-port MIMO antenna. The antenna shows pattern diversity throughout the impedance bandwidth range. The gain of the antenna varies from 4 to 8.48 dBi. The 2 band notches are achieved at 4.8 and 7.7 GHz in the UWB range. The proposed antenna is fabricated and it is found measured results are in good agreement with simulated results.The emerging wireless and mobile communication applications demand diverse and versatile antennas which are low profile, easy to fabricate and integrable with the handheld integrated circuit along with high data rate and superior quality of service. In recent wireless communication systems, the major problem is multipath fading which is due to reflection, refraction and diffraction of electromagnetic waves in free space. The problem of multipath fading can be resolved by making use of frequency diversity, spatial diversity, or polarization diversity technique. The concept of multiple input multiple output (MIMO) is very much useful for reducing the multipath fading effects thereby achieving superior data rate, range and reliability without increasing any transmit power or bandwidth. However, due to limited availability of space in the handheld devices, the placement of multiple antennas inside the device is a challenging task. Because of closely operating frequencies and space limitations the radiating elements are exposed to high mutual coupling amongst them. Therefore, there is a need for compact and efficient MIMO antenna with low mutual coupling, high isolation and unwanted frequency band suppression.As per Federal Communication Commission, the bandwidth allocated for unlicensed ultra wide band (UWB) spectrum range is from 3.1 to 10.6 GHz. 1 Due to such large operating range UWB antennas can be employed for shortrange radars, medical imaging, high data rate transmission, broadband wireless applications, and so forth. In the last few years, various designs of UWB MIMO antennas have been proposed by a number of researchers. A few of them employ simple monopole antennas with rectangular, circular, elliptical, and trapezoidal shapes with wide impedance bandwidth and improved radiation properties, 2-6 therefore, covering several mobile wireless standards. In 2 antenna structure with 2 radiating element is proposed with common...

An electrochemical device capable of manifesting reversible charge storage at the interface of an active layer offers formidable advantages, such as low switching energy and long retention time, in realizing synaptic behavior for ultralow power neuromorphic systems. Contrary to a supercapacitor-based field-effect device that is prone to low memory retention due to fast discharge, a solid electrolyte-gated ZnO thin-film device exhibiting a battery-controlled charge storage mechanism via mobile charges at its interface with tantalum oxide is demonstrated. Analysis via cyclic voltammetry and chronoamperometry uniquely distinguishes the battery behavior of these devices, with an electromotive force generated due to polarization of charges strongly dependent on the scan rate of the applied voltage. The Faradaic-type diffusion-controlled charge storage mechanism exhibited by these devices is capable of delivering robust enhancement in the channel conductance and leads to a superior ON-OFF ratio of 10-10. The nonvolatile behavior of the interface charge storage and slow diffusion of ions is utilized in efficiently emulating spike timing-dependent plasticity (STDP) at similar time scales of biological synapses and unveils the possibility of STDP behavior using multiple in-plane gates that alleviate additional requirement of waveform-shaping circuits.

The frequency response characteristics of a basic microstrip lowpass filter improved using H-shaped defected ground structures are presented. The proposed defected ground structures behave as a resonant element at high frequency and thus eliminate the stopband frequencies to achieve wide stopband rejection. The 3 dB cutoff frequency of the filter is 1.935 GHz. Due to the defects etched in the ground plane of the basic structure, the harmonic rejection is improved from 5th to 10th order along with low insertion loss and voltage standing wave ratio together with good selectivity. The compact filter has a size of 0.0338λ 2 g , with λ g = 85.18 mm being the guided wavelength at the cutoff frequency. The characteristics of the lowpass filter are verified through simulation and measurement. Consistent and stable results are obtained.

Abstract-An investigation of the distribution of the electric field within a normally-off p-channel heterostructure field-effect transistor in GaN, explains why a high requires a reduction of the thickness of oxide and the GaN channel layer. The trade-off between on-current and , responsible for the poor in E-mode devices is overcome with an additional cap AlGaN layer that modulates the electric field in itself and the oxide. A record of is achieved with a greater than in the designed E-mode p-channel MOSHFET, which is more than double that in a conventional device.

Negative capacitance transistors are a unique class of switches capable of operation beyond the Boltzmann limit to realize subthermionic switching. To date, the negative capacitance effect has been predominantly attributed to devices employing an unstable insulator with ferroelectric properties, exhibiting a two-well energy landscape, in accordance with the Landau theory. The theory and operation of a solid electrolyte field effect transistor (SE-FET) of subthreshold swing less than 60 mV/dec in the absence of a ferroelectric gate dielectric are demonstrated in this work. Unlike ferroelectric FETs that rely on a sudden switching of dipoles to achieve negative capacitance, we demonstrate a distinctive mechanism that relies on the accumulation and dispersion of ions at the interfaces of the oxide, leading to a subthreshold slope (SS) as low as 26 mV/dec in these samples. The frequency of operation of these unscaled devices lies in a few millihertz because at higher or lower frequencies, the ions in the insulator are either too fast or too slow to produce voltage amplification. This is unlike Landau switches, where the SS remains below 60 mV/dec even under quasi-static sweep of the gate bias. The proposed FETs show a higher on-current with a thicker oxide in the entire range of gate voltage, clearly distinguishing their scaling laws from those of ferroelectric FETs. Our theory, validated with experiment, demonstrates a new class of devices capable of negative capacitance that opens up alternate methods of steep switching beyond the traditional approach of ferroelectric or memristive FETs.

The aim of this paper is to present results on output power level distributions of radio base stations (RBSs) and user devices connected to a wideband code division multiple access-based third generation (3G) mobile communication network in India and relate the results to realistic human exposure to radio frequency (RF) electromagnetic field (EMF) emitted by the corresponding RBSs and the devices. The output power level distributions have been obtained through network-based measurements. In downlink, data from 868 RBSs were gathered during seven days. The RBSs were connected to five different radio network controllers (RNCs) located in different regions of India. The mean, the median, and the 95th percentile RBS output power values were found to be 24%, 21%, and 53%, respectively, of the maximum available power. In the uplink direction, output power levels of 3G devices connected to 1256 RBSs and the same five RNCs as in the downlink were assessed separately for voice, data, voice + data, and video applications. In total, more than 1 million hours of data traffic and more than 700 000 h of voice calls were measured in the uplink. The mean output power for the voice, data, the voice + data, and the video were found to be around 1%, 3%, 2%, and 4%, respectively, of the maximum available power for the 3G user devices. The findings are in line with previously published results obtained in other networks in Europe, and demonstrate that knowledge on realistic power levels is important for accurate assessments of the RF EMF exposure.INDEX TERMS Output power, power distributions, realistic exposure, UMTS, WCDMA.

In this work, a new composite transistor cell using dynamic body bias technique is proposed. This cell is based on self cascode topology. The key attractive feature of the proposed cell is that body effect is utilized to realize asymmetric threshold voltage self cascode structure. The proposed cell has nearly four times higher output impedance than its conventional version. Dynamic body bias technique increases the intrinsic gain of the proposed cell by 11.17 dB. Analytical formulation for output impedance and intrinsic gain parameters of the proposed cell has been derived using small signal analysis. The proposed cell can operate at low power supply voltage of 1 V and consumes merely 43.1 nW. PSpice simulation results using 180 nm CMOS technology from Taiwan Semiconductor Manufacturing Company (TSMC) are included to prove the unique results. The proposed cell could constitute an efficient analog Very Large Scale Integration (VLSI) cell library in the design of high gain analog integrated circuits and is particularly interesting for biomedical and instrumentation applications requiring low-voltage low-power operation capability where the processing signal frequency is very low.