Actual RF switch model or circuit in ADS

[zkywd119]

Hello everyone,

These days I'm trying to find a way to simulate the transient performance of actual RF switches (owning rise/fall time) in ADS, but I didn't figure out how to build such model. For an actual RF switch, it should contain several transistors and passive components right? I just want to find such a model or circuit containing these exact values so I can run it in ADS.

It will be really helpful if anyone can provide some suggestion about where I can find such model. Thank you!

Kevin

 

[FvM]

Recently, I did a design involving usage of a GaAs RF switch in a non-standard application. My first problem was to find how these chips actually "work", means how the transistors are connected internally and how their behaviour (power and voltage rating, signal dependent characteristic) is actually constituted, I found some answers in the papers published/linked on the skyworksinc web site. Unfortunately, I didn't yet see a complete ADS/SPICE/whatsoever model.

 

[zkywd119]

Hi FvM,

Thank you for replying. That's where I get stuck: How these components are connected internally. Because only one transistor seems to be unable to achieve RF switching function. Indeed I just want to find any existed model to see what the transient results will be.

 

[FvM]

Because only one transistor seems to be unable to achieve RF switching function.

Which switch configuration are you referring to? A usual "reflective" SPDT GaAs switch is e.g. comprised of two transistors. GaAs FETs are n-channel depletion transistors.

A special point is the relative high gate series resistor that increases the accepted RF level above a certain corner frequency. On the other hand, it restricts the possible switching speed.
https://www.skyworksinc.com/downloads/press_room/published_articles/MPD_062009.pdf

 

[zkywd119]

Thanks for that link. I think I got confused....All I want to do is to input a periodic square wave signal to the switch of on state, and observe what the output profile will be. Because for an actual switch, there exists rise time and fall time and loss. Any kind of transistor switch works for me. My problem is how to find such a transistor model in ADS and get the bias information to let the transistor work as RF switch.

Thanks a lot!

 

[FvM]

The title "actual RF switch" suggests an available RF switch IC. They are designed with special properties discussed in the said literature. If you just want a basic transistor (GaAs FET, MOSFET, whatsoever) there are plenty of available types with models.