S. Piotrowicz

State of the Art 58W, 38% PAE X-Band AlGaN/GaN HEMTs Microstrip MMIC Amplifiers

This paper presents the results obtained on X-Band GaN MMICs developed in the frame of the Kerrigan project launched by the European Defense Agency. A new step was achieved, 58 W of output power with 38% PAE in X-Band were obtained using an 18 mm 2 2-stages amplifier. To our knowledge, these results present a new state-of-the-art of X-Band MMIC power amplifiers.

Broadband Frequency Dispersion Small-Signal Modeling of the Output Conductance and Transconductance in AlInN/GaN HEMTs

Frequency dispersion of transconductance and output conductance in AlInN/GaN high electron mobility transistors is investigated in this paper. Broadband dispersion effects in the microwave frequency range are reported for the first time. A small-signal model is developed. Trapping effects are taken into account with parasitic electrical networks including distributed time constants. The model is compared with experimental data for several bias conditions and different types of dispersion.

Modeling of trap induced dispersion of large signal dynamic Characteristics of GaN HEMTs

We propose here a non-linear GaN HEMT model for CAD including a trapping effects description consistent with both small-signal and large-signal operating modes. It takes into account the dynamics of the traps and then allows to accurately model the modulated large signal characteristics that are encountered in telecommunication and radar signals. This model is elaborated through low-frequency S-parameter measurements complementary to more classical pulsed-IV characterizations. A 8×75μm AlInN/GaN HEMT model was designed and particularly validated in large-signal pulsed RF operation. It is also shown that thermal and trapping effects have opposite effects on the output conductance, thus opening the way for separate characterizations of the two effects.

43W, 52% PAE X-Band AlGaN/GaN HEMTs MMIC Amplifiers

This paper presents the results obtained on X-Band GaN MMICs developed in the frame of the Korrigan project launched by the European Defense Agency. GaN has already demonstrated excellent output power levels, nevertheless demonstration of excellent PAE associated to very high power in MMIC technology is still challenging. In this work, we present State-of-the-Art results on AlGaN/GaN MMIC amplifiers. An output power of 43W with 52% of PAE was achieved at 10.5 GHz showing that high power associated with high PAE can be obtained at X-band using MMIC GaN technology.

Broadband hybrid flip-chip 6-18 GHz AlGaN/GaN HEMT amplifiers

GaN Based HEMTs have shown superior power-frequency performances than lower band-gap materials. In this paper, we present the design of broadband hybrid 6-18 GHz amplifiers based on AlGaN/GaN HEMT technology with a flip chip approach. Measurements of a single ended amplifier based on a 0.6mm gate width device allow us to achieve more than 1.8W in the [6.5-16] GHz bandwidth corresponding to a power density of 3W/mm. A Maximum output power is obtained at 8 GHz at 2.7W corresponding to 4.5W/mm. Average typical PAE values higher than 17% in the bandwidth with a maximum of 39% were obtained. A balanced amplifier based on two single ended amplifiers was also realized. The output power is above 2.8W in the [7-17] GHz bandwidth corresponding to a power density of 2.4W/mm. Maximum output power is obtained at 7.5 GHz at 4.5W corresponding to 3.8W/mm.

Electrical performances of AlInN/GaN HEMTs. A comparison with AlGaN/GaN HEMTs with similar technological process

A study of the electrical performances of AlInN/GaN High Electron Mobility Transistors (HEMTs) on SiC substrates is presented in this paper. Four different wafers with different technological and epitaxial processes were characterized. Thanks to intensive characterizations as pulsed-IV, [S]-parameters, and load-pull measurements from S to Ku bands, it is demonstrated here that AlInN/GaN HEMTs show excellent power performances and constitute a particularly interesting alternative to AlGaN/GaN HEMTs, especially for high-frequency applications beyond the X band. The measured transistors with 250 nm gate lengths from different wafers delivered in continuous wave (cw): 10.8 W/mm with 60% associated power added efficiency (PAE) at 3,5 GHz, 6.6 W/mm with 39% associated PAE at 10.24 GHz, and 4.2 W/mm with 43% associated PAE at 18 GHz.

Design of GaN-based balanced cascode cells for wide-band distributed power amplifier

This paper reports on the design of a cascode GaN HEMT cell dedicated to 4-18 GHz flip-chip distributed power amplifier. The active device is a 8x50 mum AlGaN/GaN HEMT grown on SiC substrate. The GaN-based die which integrates the active cascode cell and its matching elements is flip-chipped via electrical bumps onto an AIN substrate. The matching elements of the balanced cascode cell are composed of series capacitances on the gate of both transistors with additional resistances to insure stability and bias path. The series capacitor on the gate of the 1st transistor is added for the distributed amplifier optimisation while the series capacitor on the gate of the 2 nd transistor is dedicated

First demonstration of AlInN/GaN HEMTs amplifiers at K band

AlInN/GaN HEMTs have shown outstanding power performances for high frequency applications, due in particular to their high current densities and their thinner barrier layers than in AlGaN/GaN HEMTs that minimize short channel effects. In this paper, we present the first published power results of two K-band hybrid amplifier demonstrators at 20GHz and 26.5GHz using 0.25µm gate length devices. At these frequencies, respectively, cw RF output power of 4.5 Watts with 20% PAE and 1.65 W with 15.5 % of PAE were obtained. These state-of-the-art results confirm the potential of AlInN/GaN technology for high frequency applications.

A Robust 11W High efficiency X-band GaInP HBT amplifier

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 mm2 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.

Ultra Compact X-Band GaInP/GaAs HBT MMIC amplifiers : 11W, 42% of PAE on 13mm2 and 8.7W, 38% of PAE on 9mm2

HBT power technology offers an excellent compromise for high power and high efficiency amplifiers up to the Ku band. In order to reduce cost and size of THALES T/R modules, we developed compact high power MMIC amplifiers with innovative transistor designs in X-band. In this paper, we present the performances of two GaInP/GaAs MMIC power amplifiers. The first one delivers an output power of 11.2W with 42.3% of PAE with a chip size of 13mm2. It represents a power density of 0.86W/mm2 of GaAs area. An advanced version on only 9 mm2 of GaAs gives an output power of 8.7W with 38% of PAE. This corresponds to a power density of 0.96W/mm2 of GaAs. To our knowledge, this is the state of the art performances in terms of power density per GaAs surface for MMIC power amplifiers above 8W. These power MMIC circuits constitute very attractive chips for phased array antennas, airborne radar, telecommunications or satellite links