A contribution to linearity improvement of a highly efficient pa for WIMAX applications

This paper describes the design of a highly efficient and linear GaN HEMT power amplifier which may be used in WiMAX application. To improve linearity of highly efficient power amplifiers, a technique using diodes in the gate DC path was applied to TL and 2HT amplifier. This solution using diodes offers a good manner to improve linearity near saturation zone compared to the approach using only a DC gate resistor for TL (tuned load) case as well as for 2HT (second harmonic tuning approach). A 2.5 GHz 2HT power amplifier circuit was built, and measured data confirm the linearity improvement, particularly near saturation zone, as predicted by simulation, maintaining higher power performances. An output power of 36.8 dBm has been measured with an associated power added efficiency of 46.5% and carrier to third order intermodulation (C/I3) of 53.4 dBc. A 2HT PA also exhibits good performances across the full (2.3-2.7) GHz band. An output power ranging from (35-36.9) dBm with an associated gain of $12.9±0.9 and a power added efficiency ranging from (40-46)% are measured across the full (2.3-2.7) GHz band.Our acknowledgment to the financial support provided by the Spanish Ministry of Science and Innovation (MICINN) through projects TEC2008-06684-C03-01 and CONSOLIDER-INGENIO 2010 CSD2008-00068

Concepción de amplificadores de potencia microondas de alto rendimiento

In this paper, we present the design of a high efficiency class-F power amplifier in pHEMT technology using an accurate WREN/COBRA model at 2GHz. The transistor is overdriven into compression in order to maximize efficiency and output power. Three concepts of output matching networks are used in the design of class F power amplifiers, based on harmonics output terminations, that is shown to have a critical influence on PA performances when compared to a classical class B power amplifier (PAE= 61.56%, Pout=12.14 dBm). The design of the first amplifier is based on 2nd harmonic termination while all other harmonics are open circuited where the output is seen to consist of a half-wave rectified voltage waveform. 87.37% saturated PAE and 12 dBm output power are obtained for this amplifier. In the second amplifier, the 3th harmonic is terminated and the output is seen to consist of a square wave voltage waveform. This amplifier result in 72.87% saturated PAE and 12.52 dBm output power. Finally, following a detailed theoretical analysis, a class F matching network that suppress the necessary load harmonics, is used for the design of the third amplifier. The saturated PAE delivered is 74.19%, the output power is 12 dBm and a square wave voltage waveform is obtained at the output

Medida de la movilidad electrónica en dispositivos GaAs: dependencia con la polarización y la frecuencia

In this paper we present a new method to evaluate mobility in GaAs devices as well as its dependence on frequency and bias point. Starting from the relationship between the high order derivative of the device drain current source, gmd, and the mobility two alternative measurement methods to obtain this parameter versus both bias conditions and frequency will be presented. At last, the experimental obtained results will show the validity of the presented approach

Study of efficiency improvement techniques for highly efficient microwave power amplifier : application to class G

Máster en Tecnologías de la Información y Comunicaciones en Redes Móviles (TICRM