about serial R&C in vdd line...

Dear all :
In PA external circuit , some company will serial res and cap in VDD line .
why they do this ?

thanks.

1) this resistor provide a voltage drop bias resistor , like the R in drain or collector in amplifiers

2) also works in supply filteration with the capacitors

Khouly

thanks khouly,

But if cap just only for supply filter function ,
why not direct put cap between vdd and gnd ?

ps :in the circuit is put serial RC between VDD and gnd .


thanks