gremlin
Newbie level 5
rf pa design
This is the first time for me to design a RF PA. I did some internal research, and I also read the famous book "RF circuit design" by Chris Bowick. I've found the chapter on PA design in this book to be useful. but I have a question after reading this book.
According to the book, when the transistor's input and load impedance are published, then the input and output are conjugately matched. An example was also given. When the input and load impedance are not published, then the collector capacitance (given in data sheet) and optimum load resistance (=(Vcc-Vce(sat))^2/2*Po ) are used to match the output.
Now I am trying to design a FM transmitter at 50 MHz using 2N3553. The data sheet does not have input and load impedance. So I can only use the latter method. The question is what do I do to match the input when there is no information available? Why the manufacturers do not publish the input and load impedance? I have a network analyzer in the lab. Maybe I can measure the input impedance and match it. Is that the only way to design the PA?
Thanks for any comments.
Andy
This is the first time for me to design a RF PA. I did some internal research, and I also read the famous book "RF circuit design" by Chris Bowick. I've found the chapter on PA design in this book to be useful. but I have a question after reading this book.
According to the book, when the transistor's input and load impedance are published, then the input and output are conjugately matched. An example was also given. When the input and load impedance are not published, then the collector capacitance (given in data sheet) and optimum load resistance (=(Vcc-Vce(sat))^2/2*Po ) are used to match the output.
Now I am trying to design a FM transmitter at 50 MHz using 2N3553. The data sheet does not have input and load impedance. So I can only use the latter method. The question is what do I do to match the input when there is no information available? Why the manufacturers do not publish the input and load impedance? I have a network analyzer in the lab. Maybe I can measure the input impedance and match it. Is that the only way to design the PA?
Thanks for any comments.
Andy