Visar resultat 1 - 5 av 67 avhandlingar innehållade ordet HEMT.
Sammanfattning : This thesis presents results on metamorphic and pseudomorpic GaAs HEMT based Voltage Controlled Oscillators and a novel high-Q varactor structure, used in the VCOs, together with a straightforward extraction procedure for the varactors.Theory and fundamentals around LC-oscillators with oscillator criteria, phase noise and different topologies are given as background together with VCO phase noise measurement methods and an overview on device flicker noise; its physical origin and measurement. LÄS MER
Sammanfattning : In most radio astronomy instrumentation, cryogenic low noise amplifiers (LNA) are used as intermediate frequency (IF) amplifiers. The system noise temperature is among the most important parameters of a receiver and requires state of the art components. LÄS MER
Sammanfattning : Indium phosphide high electron mobility transistors (InGaAs/InAlAs/InP HEMTs) exhibit the highest cut-off frequencies and the lowest microwave noise figures of all transistor technologies. Both InP HEMT technology and associated circuit demonstrators are therefore interesting to explore further. LÄS MER
Sammanfattning : The thesis considers design of low phase noise oscillators, given the boundary condition of the used technology. Important conditions are the power handling of the active device, device noise floor, the quality factor of the resonator, bias settings, and low frequency noise. LÄS MER
Sammanfattning : Gallium nitride (GaN) based high electron mobility transistor (HEMT) technology has attracted much attention during the last decade which has resulted in a rapid development in material quality and device performance. GaN HEMT microwave electronics are currently finding its applications in wireless communication infrastructure and radar systems. LÄS MER