In this paper, a Distributed Amplifier (DA) by using HEMT technology for ultra-wideband application is presented.Creation of Distributed integrated circuit has been investigated for approximately seventy years rapidly to developing semiconductor process technologies in the modern IC design. By using of this method, multiple parallel signals are combined and obtain to increase the bandwidth, enhanced power combining amplitude, and novel design capabilities for IC process. The circuit was designed and simulated in ED02AH technology by using ADS2010. The 4-stage design achieves 15.5 dB of power gain (± 0.5 dB) from 3.1 to 10.6 GHz. Reflected power of the input and output from loads matched to 50 Ohm are all below -10 dB over the bandwidth of the device, as is power transmitted from the output to the input. The device is stable for a wide range of input and output loads.

In this work, we present an analytical DC model for the Gallium Nimtide High Electron Mobility Transistor by taking into account the finite width of the two-dimensional electron gas (2DEG) layer. The model predicts the vertical electric field in the device, especially at the interface of AlGaN and GaN layers, electrostatic potential, and energy band diagram are also obtained by the model. The general form of Gauss’s law including piezoelectric and spontaneous polarization effect is employed to obtain this model in different regions from top to bottom of the GaN-HEMT. The model solves electrostatic equations in all regions of the device including two narrow regions around the AlGaN/GaN interface with thicknesses of about 3 nm. This model demonstrates how the triangular quantum well is formed around the AlGaN/GaN interface and varies as a function of gate voltages. Using the proposed electrostatic analysis and the treatment proposed by the EPFL HEMT model, the DC current-voltage characteristics are obtained by this model. The results predicted by the model are validated with TCAD simulations and in part with the EPFL HEMT model. The proposed model facilitates the following steps toward obtaining a complete model for small signal and large signal analysis of GaN HEMT.

Background and Objectives: High electron mobility transistors (HEMTs) are designed so that they are able to work at higher frequencies than conventional transistors and this has made them an attractive topic of research. Methods: Two developed designs of InGaAs/InAlAs high electron mobility transistors have been studied. The proposed laterally contacted HEMTs satisfy the desired high frequency characteristics and are good candidates for high frequency applications. Two kinds of HEMTs have been designed and simulated: single-gate laterally contacted HEMT (SGLC-HEMT) and double-gate laterally contacted HEMT (DGLC-HEMT). Results: The proposed SGLC-HEMT exhibits 111 GHz current-gain cut-off frequency. By using double-gate design, the current-gain cut-off frequency has been increased to 256 GHz. The simulation results show that the maximum oscillation frequency for the proposed SGLC and DGLC HEMTs, are 410 GHz and 768 GHz, respectively. The maximum value of transconductance (gm) for SGLC-HEMT is obtained 620 mS/mm while it is 1130 mS/mm for DGLC-HEMT. Conclusion: In order to increase the fT and fmax, instead of decreasing the gate length which is a restricted solution because of short channel effects, a very efficient structure was proposed. The designed HEMT benefits from laterally source and drain contacts. The results showed superior performance of the laterally contacted HEMTs compared to top contacted ones. The best frequency response was obtained for DGLC-HEMT. The proposed DG-HEMT design could improve the current-gain cut-off frequency and maximum oscillation frequency to 256 GHz and 768 GHz, respectively. The comparison of the performance of the DGLC-HEMT with SGLC-HEMT and with previously reported double gate HEMTs, verified the significant improvements in DC and AC characteristics of the HEMTs caused by the proposed design.

Power amplifier is one of the main components in the RF transmitters. It must provide various stringent features that can lead to complicating the design. In this paper, a new optimizing method based on the inclined planes system optimization algorithm is presented for the design of a discrete power amplifier. It is evaluated in a 2.4-3 GHz power amplifier, which is designed based on “Cree’s CGH40010F GaN HEMT”. The optimization goals are input and output return losses, Power Added Efficiency, and Gain. Large signal simulation of the optimized power amplifier shows a good performance across the bandwidth. In this frequency range, the input and output return losses are about lower than -10 dB, the Power Added Efficiency is greater than 51%, while the Gain is higher than 13.5 dB. A two-tone test with a frequency space of 1 MHz is applied for the linearity evaluation of the designed power amplifier. The obtained result shows that the power amplifier has good linearity with a low memory effect.