In this paper a systematic analysis of thermal and trapping behaviour of microwave power AlGaN/GaN HEMTs has been carried out through pulsed current-voltage (PIV) measurements and S parameters. It is shown that the thermal resistance of the device can be accurately determined provided that some assumptions on the trapping behaviour of the device are verified. The values obtained have been checked by three dimensional finite element (3D-FE) simulations with reasonable accuracy. Kink effects in the output characteristics have been analysed at different temperatures and it has been shown that they are more pronounced at ambient temperature. Finally the microwave behaviour of the device versus temperature has been assessed.

This paper reports the design and measurement of a GaN power amplifier whose output loads are optimised at fundamental and 2nd harmonic over a wide bandwidth (20%) in S-Band to reach maximum power added efficiency (PAE). The design methodology is described in the paper. Two power amplifiers have been built. The first one is optimized at fundamental and 2nd harmonic while the other one is only optimised at fundamental. Comparisons of power measurement results demonstrate the interest of optimising load impedances at the 2nd harmonic over large bandwidths for GaN HEMTs. When loaded by the matching circuit optimised at the 2nd harmonic, the packaged GaN exhibits 23.4Watts (9.7W/mm) output power associated to 15.2dB power gain and 69% PAE at the low frequency of the bandwidth (fmin). The paper also proposes a new matching architecture at 2nd harmonic frequency.

A monolithic three stage HPA has been developed for wide band applications. This MMIC is fabricated on UMS 0.25 µm GaN technology based on SiC substrate. At 18GHz, the MMIC achieved in CW mode 10W of output power with 20dB linear gain and 20% power added efficiency. The HPA provided 6 to 10W output power over 6 to 18GHz with minimum small signal gain of 18dB. These obtained performances are very promising and very close to the simulations, this will allow a very short term further improvement. This demonstration is the first MMIC on the UMS 0.25µm GaN technology.

GaN technology has gained a lot of attention in Europe over the last few years for various domains including RF electronics. After a few years of active observation, United Monolithic Semiconductors (UMS) has taken the decision to introduce a GaN technology family in its portfolio. Based on its extensive experience of III–V technology and the intensive support and collaboration with partners and European research institutes, UMS has developed the capability to produce state-of-the-art GaN devices and circuits. The present paper will summarize the current status achieved and illustrate it with a few representative examples. Aspects covering material, devices, and circuits will be addressed.

A monolithic two stages high power, high efficiency and high robustness amplifier was developed for X-band applications. The combination of the improvement of the UMS HBT process called HB20P (GalnP/GaAs) in term of breakdown, the consideration of mismatch and overdrive stability in the design. The MMIC HPA which includes a bias control circuit and a TTL interface in a surface of 18.4 mm 2 provides 11 W output power associated to a PAE of about 43% at ambient temperature and can operate at 8 dB compression with an output return loss of 1.7, in a wide temperature range. The high level of performance, the low sensitivity to the environment and the integrated biasing control make of this amplifier an excellent candidate for X band applications such as phased array active antennas.

A newmodelforGaInP/GaAs power heterojunction bipolar transistors (HBT)isproposed. This non-linear electrothermal andfully scalable modelwas designed withclosed-form equations inordertoreduce simulation timesincomplexcircuits likeHighPower Amplifiers (HPA)andtohavegoodconvergence capabilities athighcompression levels. Thispaperpresents modeltopology andshowsparameters extraction from pulsedI-V,pulsed(SI-parameters measurements. Simulations performed onatwo-stage HPA with20HBTs devices havedemonstrated thegoodconvergence properties aswellasagoodcorrelation withmeasurements. Indexterms Electrothermal Model,GaInP/GaAs PowerHBTs,convergence time.

A new model for GaInP/GaAs power heterojunction bipolar transistors (HBT) is proposed. This non-linear electrothermal and fully scalable model was designed with closed-form equations in order to reduce simulation times in complex circuits like High Power Amplifiers (HPA) and to have good convergence capabilities at high compression levels.This paper presents model topology and shows parameters extraction from pulsed I-V, pulsed [S]-parameters measurements.Simulations performed on a two-stage HPA with 20 HBTs devices have demonstrated the good convergence properties as well as a good correlation with measurements.

This paper presents an on-wafer set up for the characterization of high voltage (26V) power HBTs under simultaneous large pulsed RF signal and pulsed DC test conditions. Both RF power profiles and DC current/voltage profiles are measured thanks to the use of a pulsed VNA (for RF) and a sampling scope (for DC). Typically the pulse width range is (300 ns - 300 ms) and a 10% duty cycle is applied. RF power performances and DC consumption of the transistors under test are recorded at different time positions within the pulse width This enables to investigate the effects of transient thermal aspects on RF power characteristics. S Band Measurements of 10 Watt (20 finger 2*70mm/sup 2/ GaAs-GaInP HBTs from Thales; TRT and UMS foundry) with specific gold radiator are reported in this paper.

Ce travail rentre dans le contexte du developpement d'une filiere de transistors bipolaires a heterojonction de fortes puissances. Par rapport aux travaux deja effectues sur ce type de composants, la nouveaute reside dans les fortes tensions de fonctionnement. Les caracterisations des phenomenes d'avalanche et des effets fort courant ont donc ete necessaires. Les etapes de caracterisation ont aussi porte sur les aspects thermique et leur impact sur les performances statiques et hyperfrequence. Les modeles de quelques topologies de composants de cette filiere ont ete extraits et ont permis de realiser des investigations sur la linearite de ces composants. L'aboutissement de cette these est, a partir de ces modeles, la realisation d'un amplificateur de puissance fonctionnant en bande L avec lors de la conception un objectif quant aux performances en rendement et linearite.

It is usual to say that power GaInP/GaAs hetcrojunction bipolar transistors (HBTs) have got a lot of advantages for power amplification at microwave frequencies, because of their high gain and high power density. Furthermore, the possibility to control the base biasing conditions (voltage, current, self-bias control) compared to a field-effect transistor offers additive degrees of freedom to make a tradeoff between linearity and power-added efficiency. Nevertheless existing devices are limited because of the relatively low breakdown voltage whereas high collector voltage swings are required to achieve high power. This drawback makes them not appropriate to be used in the next generation of mobile communication base station or radar systems. Silicon technologies such as LDMOS and III-V devices (MESFET and HFET) [1]. present competitive performances in term of high power level but for medium power added efficiency. Important improvements have been done in the last years which make possible large breakdown voltages on GaInP/GaAs HBTs. Breakdown value close to 67 V has,been achieved. The aim of this work is to significantly improve the modeling of the breakdown voltage on that kind of transistor. Furthermore the in depth characterization and modeling of self-heating effects has been greatly improved in order to improve thermal management solutions which enable to enhanced design solutions of HBT high power amplifiers.

The breakdown values of GaInP/GaAs HBTs have been strongly increased, keeping constant RF performance. A 67 V common base breakdown voltage (BVcb0) is obtained associated with a 37 V collector emitter breakdown value (BVce0). Such devices have great potential for use in base stations as power amplifiers where 10 W (linear) and 100 W (compressed) output powers are needed. For such powers, transistors work close to the breakdown limit. Therefore, accurate modelling of both static and dynamic breakdown phenomena becomes important for the optimum design of reliable amplifiers. This is the purpose of this paper. The base-collector breakdown of a 16-finger HBT transistor has been characterised in the cases of constant base current and constant base voltage biasing conditions. An HBT model accounting for breakdown is presented and large signal load pull measurements reported.