Active modules

Circuits and Components for system evaluations and design

4.3  Active modules

The definition of active devices is not extremely logical, but most RF engineers considera ll elements containing semiconductor devices to be active, although diodes, for instance, can be operated in an entirely passive fashion.  They do not always need a dc bias and they do not convert dc energy into RF. AN RF switch is an interesting example.   

If made of mechanically operated parts, many of us would say it is passive.    However, if the same functional task is handled by a set of PIN diodes, manufacturees list it as active.   Modules containing bipolar devices or FETs are easier to classify, which is also true of all microwave tuve amplifier and oscillator circuits.


                                                  


Figure 4.10 An isolator can be used to protect PAs from destruction due to severe mismatch and to reduce load-pulling effects in oscillators.


                                                          

Figure 4.11 A ferrite circulator can be used as the key element of a TX/RX switch in a single antenna system (radar or communication equipment).    The output power is reduced by the insertion loss, and there is additional attenuation in the RX path, making the equivalent NF larger.

Pagina fuente:  http://books.google.co.ve/books?id=63_zqr7w9OoC&pg=PA63&lpg=PA63&dq=Circuits+and+Components+for+system+evaluations&source=bl&ots=wynYdLf_wJ&sig=pYFYYhrXuw-CR9rSUZHIkfW0TdM&hl=es&ei=Z0ZrS8a9Msmj8AaR5-2EBg&sa=X&oi=book_result&ct=result&resnum=9&ved=0CDYQ6AEwCA#v=onepage&q=Circuits%20and%20Components%20for%20system%20evaluations&f=false

Libro:  Circuits and Components for System Evaluations and Design

Autor: Pekka Eskelinen

Nombre: Josmar Eduardo Depablos Rodriguez

Asignatura: Circuitos de Alta Frecuencia

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