Majlesi Journal of Telecommunication Devices
Volume:3 Issue: 3, Sep 2014

In this paper, a new ultra-low-voltage ultra-low-power operational transconductance amplifier (OTA) using feed-forward technique is proposed. The proposed topology is based on a bulk driven input differential pair employs a gain-stage in the Miller capacitor feedback path to improve the pole-splitting effect. In addition, through a coupling capacitance, input signal is simultaneously coupled to gate of idle transistors resulted dramatic enhancement in gain and unity gain-bandwidth (UGB) of the OTA. The circuit is designed in the 0.18µm CMOS technology. The simulation results show that the amplifier has a 90dB open-loop DC gain and a unity gain-bandwidth of 270 kHz while operating at 0.5V supply voltage. This technique show remarkable enhancement in unity gain-bandwidth and also in DC gain compared to the bulk driven input differential pair technique. The total power consumption is as low as 900nW which makes it suitable for low-power bio-medical applications.

This paper presents a 6 to 64 GHz passive distributed drain mixer implemented by using a standard 0.13 um CMOS process. To improve the bandwidth, low conversion loss and low noise figure, filtering structures is utilized for wideband matching. Both Chebyshev and Butterworth filters are used instead of the classical constant-k sections of the conventional DA in order to form respectively the gate and drain transmission lines. This mixer consumes zero dc power and exhibits a conversion loss of 4.9-7.9 dB and noise figure (DSB) of 6.8-8.1 dB from 6 to 64 GHz.

In this paper a new cascode class E power amplifier with a driving stage of class F and novel output network is proposed. Class F power Amplifier is able to produce square waves, used in driving of main stage, owing to use main frequency and third frequency harmonic. The proposed output network has also improved the parameters of circuit like efficiency, power added efficiency and output power with adding a capacitor and an inductor. In order to have more real results the circuit has been redesigned and simulated using spiral inductors.The simulation has taken place using 0.18 µm CMOS technology in ADS simulator software based on IEEE 802. 11b utilized in 2.4 GHz and WLAN applications. Proposed circuit delivers 23.1 dBm power; out of a 1.8 supply voltage to a 50Ω load with 84.3% efficiency and 80.4 % power added efficiency in 2.4 GHZ operating frequency.

This paper presents a study of hard combination data fusion for cooperative spectrum sensing in Cognitive Radio (CR). Fast and accurate spectrum sensing is crucial in realizing a reliable cognitive network. Cooperative spectrum sensing can help reducing the mean detection time and increasing the agility of the sensing process. However, when the number of cognitive users is large, the bandwidth need for the control channel that are used to report the secondary user nodes’ results to the fusion center may become excessively large. This paper presents a hard decision-based cooperative sequential detection scheme to reduce the average sensing time that is required to reach a detection decision. In the scheme, each cognitive radio computes the log likelihood ratio for its every measurement, and quantizes its measurements then sends its hard-decision to base station and the base station sequentially accumulates these log likelihood statistics and determines whether to stop making measurement.

Over the years, the discussion about achieving knowledge and discovering unknowns have attracted a lot of people and occasionally a news or text or short understanding of a new science absorbs scholars and people motivated to learn. looking in to the modern technology, we see new inventions and innovations which are unique. as an example, over the past years, new technology has been created in computer networks of which metro Ethernet has had a Noticeable advance in urban communication. therefore the aim of this article is to provide and compile information regarding metro Ethernet technology. utilizing Ethernet in urban networks need the developing potential and strength that only exist in MPLS and IP levels. layer two and three joint networks are solutions that join simplicity and economy of Ethernet at IP/MPLS scale. Different transfer technologies have been used in metro so metro services should be given on a mixture of optic and data switches, MPLS have been developed for this work and using generalized-MPLScontrol surface that support both data and optic switches performs it. In the beginning theories about using metro technology to produce urban networks are explained. then a simulating called eNSP which is a suitable alternative for simulating metro Ethernet technology and at the end the result of the simulation will be presented.

In this paper, formulation of the problem of plane wave diffraction by a wedge with anisotropic impedances is given for the case of almost grazing incidence. All steps of problem are given in detailed. Wedge is a canonic structure and diffraction from wedge may be used in modelling scattering from a variety of complex structures. In this study, by using the Maxwell’s equations the field components can be expressed in terms of z-components. By applying appropriate boundary conditions, a coupled system of equations is obtained in terms of field component and derivatives of field components with respect to and r. By using similarity transform to the coupled system of equations, the coupling is reduced to the simplest form in which Malyuzhinets theorem can be applied. The solution of field components is sought in the form of Sommerfeld integrals. The Malyuzhinets theorem is applied to the Sommerfeld integrals. By using Sommerfeld integrals the problem is reduced to a system of coupled functional equations. Solution of homogeneous functional equations is given in terms of χф functions. For a small parameter of the problem (sinθ0<<1 where θ0 is the angle between z-axis and incident wave) the perturbation procedure is used to reduce the coupled functional equations to a system of linear equations with this small parameter being at the integral terms of equations. As a result the closed form solution is given for functional equations. The obtained analytic expression for the spectral functions is substituted to the Sommerfeld integrals, which are evaluated by means of steepest descent technique.Then, the analytical expressions for the diffraction coefficient for both magnetic and electric field components are derived. Considering these different geometries and small skewness angle, it is concluded that this approach enlarge the class of solvable diffraction problem in a small range. Additionally, the results are valuable for the comparison purposes for the other approximate methods.

A 10 bit Low power 666KS/s successive approximation register is presented. Monotonic capacitor-switching has been employed to reduce the switching energy power and total capacitance by 81% and 50% respectively. The ADC achieves an SNDR of 53.6 dB and ENOB of 8.61, while the power consumption and supply voltage are 0.83mW and 1.2V respectively. all simulations are carried out using cadence simulating software in 0.18um technology.