Maximum Stable Power Gain Research Articles

Power gain assessment of ITO based Transparent Gate Recessed Channel (TGRC) MOSFET for RF/wireless applications

In this work, power gain assessment and intrinsic delay of Transparent Gate Recessed Channel (TGRC) MOSFET have been observed for RF applications and the results so obtained have been compared with Conventional Recessed Channel (CRC) MOSFET. Simulation results show that TGRC architecture has significantly improved the power gains in terms of maximum available power gain (Gma), maximum transducer power gain (GMT), maximum stable power gain (Gms) and appreciable reduction in intrinsic delay as compared to CRC-MOSFET owing to indium tin oxide (ITO) in recessed channel as a conducting gate material and thus providing its efficacy for low power switching applications. Further, effect of gate length scaling has also been observed on TGRC MOSFET and it has been found that the cut-off frequency (fT) and maximum oscillator frequency (fMAX) enhances by 66% and 36% respectively as channel length scales down to 20 nm. Further, the effect of negative junction depth, oxide thickness and substrate doping have also been investigated for TGRC-MOSFET. This TCAD assessment has been done at frequencies of several THz which fortify its use for high frequency RF/wireless applications.

On The Operation Configuration of SiGe HBTs Based on Power Gain Analysis

The power gain difference, under different device stability conditions, between common-emitter (CE) and common-base (CB) bipolar junction transistors (BJT) is analyzed comprehensively. The analysis reveals that the CB configuration offers higher maximum available power gain than the CE configuration in the device's high operation frequency range, while the inverse relation holds in the very low frequency range. In the intermediate frequency range, the base resistance value, mainly affected by the base doping concentration, determines which configuration offers higher maximum stable power gain (MSG). These analyses have explicit implications on the operation configurations of SiGe heterojunction bipolar transistors (HBTs). Employing a typical doping profile of Si bipolar junction transistors with a trapezoidal Ge profile in SiGe HBTs usually results in a larger base resistance than the emitter resistance. For these devices, the CE configuration exhibits higher MSG than the CB configuration. Employing a higher base doping concentration than the emitter with a box-type Ge profile considerably reduces the base resistance and thus favors the CB configuration for power amplification in this frequency range. The analysis are quantitatively verified with simulation and measurement results from SiGe HBTs of representative Ge and base doping profiles.

Microwave Simulation on the Performance of High Power GaN/AlGaN Heterostructure Field Effect Transistors

We present the results of the simulation of dc and microwave performance of a GaN/AlGaN heterostructure field effect transistors and compare the results with recent record-breaking experimental data from Cree Research, Inc. Our simulation results are in good agreement with the data on the small signal transistor performance. The calculated maximum stable power gain decreases with frequency with a 3 dB per octave slope in agreement with experimental results. The simulated values of the saturation power are somewhat less than experimentally measured values. This difference might be caused by self-heating, which is smaller at microwave frequencies than at dc.

Complete sliced model of microwave FET's and comparison with lumped model and experimental results

This paper describes a rigorous and systematic procedure to derive a unified and complete semidistributed FET model that can be easily implemented in CAD routines of simulators. We have used the three coupled-line theory, including active and passive electromagnetic coupling between the semiconductor electrodes. The analytical formulas are given in order to calculate the capacitances of the electrodes and sufficient agreement is obtained in comparison with numerical analysis. For the first time, the experimental data of the device are compared with full three coupled-line theory and three coupled-line sliced model. This full semidistributed approach to FET modeling is applied to the analysis of a submicrometer-gate GaAs FET at centimeter and millimeter-wave frequencies, and the results are compared with the lumped element approach. The maximum available power gain (MAG) and the maximum stable power gain (MSG) of the device are calculated as a function of device width and frequency. Both the losses caused by the channel and those caused by the finite electrode conductivity are included. Good agreement is obtained between theory and experiment.

Application of anodization in Oxygen plasma to fabrication of GaAs IGFET's

Anodic oxide grown in oxygen plasma has been used to fabricate the gate insulator of GaAs insulated-gate field-effect transistors (IGFET's), by patterning the gate electrode of 1.2 µm in length with the dry etching process. It is found that the oxidation process does not damage the electrical property of the channel layer. However, the trap states at the interface between the oxide and the channel affect the low-frequency characteristics, especially at positive gate voltage. The IGFET's show a good high-frequency performance comparable to GaAs MESFET's. The following characteristics are confirmed from the measurement of the S-parameters and the equivalent circuit analysis; the maximum stable power gain is 11.4 dB at 8 GHz, the cut-off frequency of the unilateral power gain is 48 GHz, and the intrinsic gain-bandwidth product is 18 GHz. The minimum noise figure is measured to be 4.8 dB at 8 GHz.

Stability and Power Gain of Tuned Transistor Amplifiers

The transistor is a nonunilateral device which, if appropriately terminated, can become unstable at frequencies where its "internal feedback" is sufficiently large. At such frequencies, the maximum power gain is infinite and the transistor may oscillate. This paper discusses the maximum power gain realizable as a function of a required degree of stability. A "stability factor" is defined in terms of the transistor parameters and terminations (the admittance matrix is used as an example, but the approach is analogous using other representations). The maximum stable power gain of an isolated amplifier stage and the terminating admittances required for the realization of this maximum power gain are then computed as functions of the stability factor. The computations are extended to include bandwidth requirements and limitations. (It is found that, although bandwidth requirements may impose limitations on the power gain, there is no simple relationship tying together bandwidth and power gain.) The treatment of multistage amplifiers is outlined with the conclusion that the gain realizable in an n-stage amplifier is smaller than n times the gain of a one-stage amplifier having the same stability factor as the stages of the n-stage amplifier. The respective advantages of different representations for different circuit configurations are discussed. In an appendix, the theoretical considerations are applied to tuned transistor amplifiers in common-emitter and common-base configurations. The stability factor is related to the tolerances in transistor parameters and terminating impedances. Examples are given for the maximum realizable stable gain as function of parameter tolerances.