ADS Design of 19GHz GaAs LNA, Inquiry Regarding By-pass Capacitor Size Selection

[Bailey_NTF]

I am currently using ADS software to design a GaAs LNA with a center frequency of 19GHz. In the circuit design, I need to use by-pass capacitors to stabilize the power supply and filter out noise. I would like to ask you about how to choose the size (capacitance value, package, etc.) of the by-pass capacitors for this high-frequency application.
I hope you can provide valuable advice and share your experiences. Thank you!

 

[BigBoss]

You should place few capacitors in parallel on DC line for different bands. For DC, for Low Frequencies, for High Frequencies, for Higher Frequencies.
While you choose these capacitors, you have to pay attention their self-resonance frequencies. Their value should be as high as possible but slightly lower than SRF.
And quality, you have to select good and well-known brands such as Johansson, Kemet, Kyocera, Murata.

 

[Bailey_NTF]

I apologize for not explaining clearly earlier. I am using the manufacturing process from Win Semiconductor to design an LNA. I am struggling with how to choose the bypass capacitor. Could you let me know which formula you mentioned for self-resonance? Are the Terminals both connected to 50 Ohms?

 

[BigBoss]

I apologize for not explaining clearly earlier. I am using the manufacturing process from Win Semiconductor to design an LNA. I am struggling with how to choose the bypass capacitor. Could you let me know which formula you mentioned for self-resonance? Are the Terminals both connected to 50 Ohms?

I don't think there are de-coupling capacitors in WIN PDK. There are generally MiM capacitors (very low values) in MMIC PDKs and therefore your have to use them off-chip.Self resonance frequency depends on capacitor's geometry, di-electric material and this must be mentioned in PDKs design guide.