SPST switch for 5.7 GHz TMAA

lazy_frog · 2024-12-22T16:02:50+0000

Hi guys, I am currently designing a spst switch using "bar63-02l" PIN diode and am unable to analyze what is wrong with my circuit , the dc blocking capacitor and rf chokes are put so that they allow and deny the RF signal respectively, and a dc bias of 1V and -1V is given (for it to work in ON and OFF state respectively). Need help in improving the circuit and suppressing the rf signal when pin diode is off.

FvM · 2024-12-22T16:20:36+0000

10 dBm is 0.7 Vrms respectively 2 Vpp, more into open circuit. Can be hardly switched with only +/- 1 V control signal, neither fully on nor off.

lazy_frog · 2024-12-22T16:25:29+0000

FvM said:
10 dBm is 0.7 Vrms respectively 2 Vpp, more into open circuit. Can be hardly switched with only +/- 1 V control signal, neither fully on nor off.

Should I increase the control signal and decrease the rf signal power?

BigBoss · 2024-12-22T16:42:33+0000

This PIN Diode has up to 3 GHz Operating Frequency specification. Internal junction capacitance is higher than 0.5pF@5.7GHz (rough estimation).
So, it's not very appropriate choice for 5.7GHz.

vfone · 2024-12-22T19:57:14+0000

Place the PIN diode in shunt configuration (cathode to the ground), remove L2 from the circuit and use another 5pF capacitor to go to Port 2. You get better attenuation in this configuration compared to series mode.
Use initially a tunable DC supply to bias the PIN diode, instead of a pulsed signal, to find which is the optimum DC range for the diode vs attenuation.
In this configuration looks like BAR63 works fine even at 5GHz.

SPST switch for 5.7 GHz TMAA

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SPST switch for 5.7 GHz TMAA

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