Dummyeng
Member level 4
Hello
I design a switch with pin diode but I couldn’t recognize about impedance matching stay correct or not.
Here is my design
excuse me for bad shape
When large signal come (60 dbm 18 GHz) it(diode) should be off but in small signal ( -20 dbm ) should be on and nothing receive to antenna neither return loss to rfin and all should go to gnd.
When it is off I think that it is like an stub and change my impedance is it correct?
And when it is on should I connect directly to gnd?
is it correct I place R1 before diode because I saw only place after diode in rf applications?
And I don’t consider about duty cycle in my design.
I gave my reverse voltage according to AN3022 mycom It says “For p-i-n diodes with I-region thickness less
than approximately 1 mil (25 μM), an external dc reverse bias equal to the peak RF voltage is required, regardless
of duty cycle. This reverse bias requirement is relaxed, however, for thicker p-i-n diodes and low RF duty cycles
(D) so that 10 mil (250 μM) diode requires at most 35 V reverse bias to keep within the conditionally safe reverse
bias region under any duty cycle.”
I design a switch with pin diode but I couldn’t recognize about impedance matching stay correct or not.
Here is my design
excuse me for bad shape
When large signal come (60 dbm 18 GHz) it(diode) should be off but in small signal ( -20 dbm ) should be on and nothing receive to antenna neither return loss to rfin and all should go to gnd.
When it is off I think that it is like an stub and change my impedance is it correct?
And when it is on should I connect directly to gnd?
is it correct I place R1 before diode because I saw only place after diode in rf applications?
And I don’t consider about duty cycle in my design.
I gave my reverse voltage according to AN3022 mycom It says “For p-i-n diodes with I-region thickness less
than approximately 1 mil (25 μM), an external dc reverse bias equal to the peak RF voltage is required, regardless
of duty cycle. This reverse bias requirement is relaxed, however, for thicker p-i-n diodes and low RF duty cycles
(D) so that 10 mil (250 μM) diode requires at most 35 V reverse bias to keep within the conditionally safe reverse
bias region under any duty cycle.”