An 8-18 GHz broadband high power amplifier(HPA) with a hybrid integrated circuit(HIC) is designed and fabricated.This HPA is achieved with the use of a 4-fingered micro-strip Lange coupler in a GaAs MMIC process.In order to decrease electromagnetic interference,a multilayer AlN material with good heat dissipation is adopted as the carrier of the power amplifier.When the input power is 25 dBm,the saturated power of the continuous wave(CW) outputted by the power amplifier is more than 39 dBm within the frequency range of 8-13 GHz,while it is more than 38.6 dBm within other frequency ranges.We obtain the peak power output,39.4 dBm,at the frequency of 11.9 GHz.In the whole frequency band,the power-added efficiency is more than 18%.When the input power is 18 dBm,the small signal gain is 15.7±0.7 dB.The dimensions of the HPA are 25×15×1.5 mm^3.
The growth by molecular beam epitaxy of high quality GaAs epilayers on nonmisoriented GaAs(111)B substrates is reported.Growth control of the GaAs epilayers is achieved via in situ,real time measurement of the specular beam intensity of reflection high-energy electron diffraction(RHEED).Static surface phase maps of GaAs(111)B have been generated for a variety of incident As flux and substrate temperature conditions.The dependence of GaAs(111)B surface reconstruction phases on growth parameters is discussed.The(19^(1/2)×19^(1/2)) surface reconstruction is identified to be the optimum starting surface for the latter growth of mirror-smooth epilayers.Regimes of growth conditions are optimized in terms of the static surface phase diagram and the temporal RHEED intensity oscillations.
