Impedance Reshaping and Stability Analysis of the Unbalanced Three-phase System Considering the Grid-tied Inverter based Imbalance Compensation

Grid-tied inverters have been adopted both as the interface of renewable energy resources and as a solution to address power quality issues. To compensate the imbalance distortion caused by asymmetric local load, DQ transformation based compensation method is introduced into the control scheme of the grid-tied inverter. Taking both the inverter control scheme and circuit topology into account, the space vector based impedance modelling and stability analysis approaches are proposed in this paper to analyse the dynamic of the asymmetric system with active imbalance compensation. The proposed impedance models indicate that the compensation control method can reshape the output impedance features, and affect the stability of the system. The stability analysis results are verified in this paper by experimental results.

Comparative Analysis of CNTFET Models through the Design of a Differential Amplifier

In this paper we compare simulation results on a differential pair circuit using a CNTFET model, already proposed by us, with the result obtained using Stanford model. We study the case of differential pair with differential input and single ended output as core of a 50 GHz amplifier for mm waves band. We consider the case of a CNTFET having a single CNT tube with indices (19,0) and 25 nm long. For this circuit we present result for its main parameters: gain, input impedance, output impedance, noise and distortion. Since the Stanford model includes fixed capacitance, for comparison we applied the same capacitance on our model. Since this capacitances dominate the high frequency cut, results are not much different, except for the lack of noise modelling in the Stanford model.

Computation of Constant Gain and NF Circles for 60 GHz Ultra-low noise Amplifiers

Wireless communication is a constantly evolving and forging domain. The action of the RF input module is critical in the radio frequency signal communication link. This paper discusses the design of a RF high frequency transistor amplifier for unlicensed 60 GHz applications. The Transistor used for analysis is a FET amplifier, operated at 60GHz with 10 mA at 6.0 V. The simulation of the amplifier is made with the Open Source Scilab 6.0.1 console software. The MESFET is biased such that Sll = 0.9<30°, S12 = 0.21<-60°, S21= 2.51<-80°, and S22 = 0.21<-15o. It is found that the transistor is unconditionally stable and hence unilateral approximation can be employed. With these assumptions, the maximum value of source gain of the amplifier is found to be at 7.212 dB and the various constant source gain circles and noise figure circles are computed. The transistor has the following noise parameters: Fmin = 3 dB, Rn = 4 Ω, and Γopt = 0.485<155°. The amplifier is designed to have an input and output impedance of 50 ohms which is considered as the reference impedance.