and check if your lines are really 50ohm, ie if you are able to print a quick pcb, put only 50 ohm straight line with same lenght on your phase shifter pcb and measure s11 and s21 of the line with same type of sma connectors
good luck
1. But is this kind of behavior common with rf ic ? I mean its totally different from what they have shown in data sheet.
For the "digital" signals, you have used a narrow line of unknown length - possible difference. You can decouple the digital line by using a large series resistors very close to the switch. From what I have seen in the data sheet, the control signal has very little current, so the resistor will pass the control signal and decouple possible RF signals.
1. Should I give separate control signal for each switch?
2. I bought 1000pF 1206 package smd cap for the decoupling. Should I place large series resistor ( as you have said) with these 1000pF to the ground and as close to the pins as possible?
3. In the given PCB, I have used different package 100 pF cap ( As you can see some are large while others are small) will they make any difference?
I would taper the lines at the switch, to reduce the discontinuity.
This will also give room to place the ground via near the switch.
2. As for the 4.7 kohm resistor, isn't it already available in the switch?
I am designing a phase array antenna for my final year project. For phase shifting part I am using skyworks SPDT Switch AS213-92LF. As there is no model available for simulating the switch, so I directly designed and tested the phase shifter. The PCB is shown in the picture. It is not final PCB, as you can see. The problem is that I am getting S11 about -6 db, S22 about -7 and S12 about -10 db, which is very poor performance. Please tell me what can I do to improve performance. I am using 50 ohm line on FR-4 substrate and operating frequency is 2.4 GHz. Please its urgent.View attachment 77936
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