3. Tripoles (transistors)

While the use of diodes for oscillators is fairly straightforward, the same cannot be said for amplifiers. For this application, it's preferable to use transistors, which are much simpler to use and highly efficient for both low signal-low noise and power applications. Two families of transistors are used in microwave applications: bipolar transistors and field-effect transistors. Over the past decade, the structure of these components has evolved thanks to enormous advances in microlithography, epitaxial growth and ion implantation techniques. These advances have made it possible to significantly reduce the horizontal (microlithography) and vertical (epitaxy) dimensions of the components. The use of heterojunctions in bipolar and field-effect structures has led to considerable improvements in transistor performance (gain, noise figure, power).