Marino J. Martinez

A true enhancement mode device technology suitable for dual mode dual band power amplifier applications

We have developed a true enhancement mode AlGaAs/InGaAs heterostructure insulated-gate FET technology that combines single supply operation with state-of-the-art linearity and efficiency performance for both digital and analog portable communications. The measured linearity and efficiency performance of this technology rivals or surpasses the results achieved by PHEMT and HBT devices reported to date. For the NADC modulation format at 1800 MHz and VDS=3.6 V, a power-added efficiency of 50% has been achieved at +30.6 dBm output power, -30 dBc adjacent channel power and -49 dBc alternate channel power.

P-HEMTs for low-voltage portable applications using filled gate fabrication process

A fundamental change in gate formation to a filled gate process was combined with changes in film deposition. The resulting p-HEMT manufacturing process gives much better performance for low-voltage RF amplification. At a drain voltage of 3.5 V, a 12-mm periphery device fabricated by this method is capable of 33 dBm output power with an associated power-added efficiency of greater than 75%.

A single supply device technology for wireless applications

Single supply power amplifiers have become the new paradigm in portable phone handsets due to the recent availability of HBT and pseudo enhancement mode PHEMT technology. We have developed a true enhancement mode heterostructure insulated-gate FET device (HIGFET) which is suitable for use in both digital and analog power amplifiers and in addition to this, shows promise for use in small signal receiver applications.

AlGaAs/InGaAs power P-HEMTs for high-efficiency, low-voltage portable applications

Power Pseudomorphic High Electron Mobility Transistors (P-HEMTs) with unprecedented efficiency are being produced for low-voltage portable wireless products. 12 mm devices operating at 3.5 V achieve more than 75% power added efficiency, 1.5 W output power, and 11.5 dB gain, simultaneously, at a frequency of 850 MHz.

NiGeW ohmic contacts on GaAs heterostructure epitaxial layers

Abstract NiGeW has been successfully implemented as a contact material on GaAs MESFETs in a production environment. However, when identical contacts were used on heterostructure field effect transistors (HFETs), a strong interaction was observed between NiGeW and GaAs/AlGaAs epitaxial layers after annealing. Although NiGeW was considered a refractory contact and was not expected to react with the substrate, we detected defects at the GaAs/AlGaAs interface by cross-sectional transmission electron microscopy. These electrically active defects degrade the HFET performance significantly. As a result, the HFET epitaxial structure had to be re-optimized in order to minimize the observed adverse effect.