|
Title: Simple Method for Pi-Networks for a Range of Output Impedances Post by: IN3IEX on October 04, 2011, 05:20:51 AM The design of Pi networks for output stages is often difficult and requires a number of iterations. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Here I present a direct method that can traslate your requirements directly into components values. http://www.ing.unitn.it/~fontana/SimpleP.pdf There is no need to define Q. Pay attention using this method with class C output stages, because Q can be very low at low output impedances. To know how much of the Smith chart you can cover with your matching network at a given frequency just use this DOS software: http://www.science.unitn.it/~fontana/rfmatch.html Use Montecarlo simulation and define the nominal value and tolerance of the capacitors in order to obtain the maximum and minimum value of capacitance of your components. The inductor should have 0% tolerance. For instance 100 pF nominal and 80% tolerance will produce capacitances between 20 pF and 180 pF. Examples: http://www.ing.unitn.it/~fontana/antmatch.pdf Best regards Giorgio |