Resistor Choice for Wilkinson Power Divider

[etothe456t]

wilkinson divider without resistor

I'm designing a 50ohm Wilkinson Power Divider... I know that I'm trying to find a resistor that will have the lowest parasitic capacitance in parallel w/ the resistance, so what type of capacitor would be best? Metal Film? Max Frequency ~100-300MHz

thanks

 

[biff44]

what is resister wilkinson power divider

300 MHz? With an "M"?

You can use any type of resistor you want at those frequencies.

 

[etothe456t]

wilkinson divider resistive

so you would say its safe to assume the parasitic capacitance is less then 1pF? Because I think the resistance would roll off if it was greater then that...(see matlab code). I didn't know if there was a specific type of resistor that was better suited to low parasitic capacitance, or if the size was an issue in which case I should go with a smaller SMT resistor... what do you think?


clc;
clear all;
close all;

f = 1:100:300e6;

L = 10e-9;

C1 = 1e-12;
C2 = 5e-12;
C3 = 10e-12;

R = 100;

Z1 = sqrt(((2*pi*f*L).^2 + R.^2) ./ ((1-(2*pi*f).^2*L*C1).^2 + (2*pi*f*R*C1).^2));
Z2 = sqrt(((2*pi*f*L).^2 + R.^2) ./ ((1-(2*pi*f).^2*L*C2).^2 + (2*pi*f*R*C2).^2));
Z3 = sqrt(((2*pi*f*L).^2 + R.^2) ./ ((1-(2*pi*f).^2*L*C3).^2 + (2*pi*f*R*C3).^2));

plot(f,Z1)
hold on;
plot(f,Z2,'-r')
plot(f,Z3,'-g')

 

[FvM]

resistive wilkinson power divider

See this paper http://indeedzcr.googlepages.com/FrequencyResponseofThinFilmChipResistors.pdf

 

[karote]

300 mhz wilkinson power divider

I have used resistive dividers @ 3 GHz with no problem. Of course you get a losses compared to conventional wilkinson divider. But in case you do not mind burning half of the power in the divider resistors and you don't mind that the isolation between output ports is only 6 dBs, then resistive power divider is most simple solution (and cheap) use 50 ohm resistors in "triangle connection" and 18 ohm in "star connection"