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Help me with very high speed RF switch design

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scoppulal

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rf switch

HI ALL!

I'm working on a project that involves a VERY HIGH SPEED RF SWITCH,
it will work on HF.
The range should be 1-30 MHZ.

Can anybody help with ideas on the device to use?

Thanks in advance.
 

Re: RF SWITCH

You can use a PIN-diode switch. See

**broken link removed**
**broken link removed**
 

RF SWITCH

Mechanical: 20...500 msec, highest isolation, higher cost.
PIN: usec range, moderate isolation, high cost
GaAs FET switch: nsec and subnsec range, moderate to high isolation, the most cheaper.
 

Re: RF SWITCH

scoppulal said:
HI ALL!

I'm working on a project that involves a VERY HIGH SPEED RF SWITCH,
it will work on HF.
The range should be 1-30 MHZ.

Can anybody help with ideas on the device to use?

Thanks in advance.
Click to expand...

Range is not that big unless is else. See David Pozar "Microwave Engineering" book how to use PIN diodes recomended here by others as switches. You have sample schematics there.
 

Re: RF SWITCH

You also need to specify the power level and off isolation. Transistor switches come in IC form with their drivers. They are not as fast as PIN types but they work over a wide frequency range. The problem with PIN types is that they have a lower frequency limit. Read the data sheet carefully when you make a selection.

Your idea of very fast may not be doable on the HF range. The frequency spread of starting a waveform with near zero rise time spreads the signal over a very wide frequency range. The bandwidth of your receiving system will slow the rising edge down and ruin your desired switching time.
 

Re: RF SWITCH

Pins gives lower I.L compared to MESFET. The Schotkey diode(gate port) is faster compared to the PIN. Transistor will be at saturation at the 1dBC power. Generaly speaking the device is not the lomiter but the driver.
D.J
 

Re: RF SWITCH

the power involved should be about 30-50W RF

Is it possible to use the devices named before with this level of RF power?

Thanks
 

Re: RF SWITCH

At your power level you will have to use PIN diodes. The GaAs switches I described above are for mW signals and lower.
 

Re: RF SWITCH

I'm familiar with the mm waves range- up to 94GHz. You are looking for 1 to 30MHz. Fast active device is more than mW. for example using PHEMT for 40GHz befoe 1dB Compression you can have less than 1W. Using shotckey diode (Gate of Mesfet etc)for fast responce the power cannot go up to 30W. PIN works!!!

D.J
 

Any one knows how to simulate switch speed in ADS? THANKS!

for example , an TR SW, when Vtx =1, Vrx =0, TX chain will be on. when Vtx =0, Vrx =1, RX chain will be on.

In transient simulation, I use pulsed V for Vtx. I would like to plot how Vout follow Vtx in time domain to check the speed,right ? any thoughts?
 

varuniyengar said:
RF MEMS are a viable option!!
Click to expand...

yes surely it has benefits over PIN/FET designs in terms of power loss and isolation but not many architectures are available in redundancy switches area which find applications in space communication.if anyone has a set of 4 port designs, please forward me!! i am looking for design topologies!!:roll::roll:
 

Hi,
are there low profile around 1mm hieght RF MEMs switches?
i tried to find some Rf switches but w/o sucsses in this forum recomended me RF relay but i couldn't find somehing that will be low profile , so now i try RF mems or pin diodes .
here is my specification for the Switch:
Please see below the RF analog ac switch specification:

- Operation frequencies: 0-20MHz

- SPST or SPDT

- Application: pass around 6W in Lo freq, block around 10mW in Hi freq

- Close/on state (when around 3Vdc applied to the switch controls):
Can pass 6Watt, 25Vac pp @ sub 0.5MHz

- Rds on: up to 200mOhm when switch is on state for minimal loss

- Open/off state (when no any power applied to the switch- normally off):
Can block 25Vac pp @ above 10MHz signal w isolation around 20dB

- Low profile: SMT part, preferably around 1mm height

- Target price: up to 2$ per unit
 

well you have taken the right direction. I am also working in this area but havnt found appropriate literature. If you have found some, can you please quote the source?
I will try to share relevant information as and when I get them.

thanks
soumendu

levnu said:
Hi,
are there low profile around 1mm hieght RF MEMs switches?
i tried to find some Rf switches but w/o sucsses in this forum recomended me RF relay but i couldn't find somehing that will be low profile , so now i try RF mems or pin diodes .
here is my specification for the Switch:
Please see below the RF analog ac switch specification:

- Operation frequencies: 0-20MHz

- SPST or SPDT

- Application: pass around 6W in Lo freq, block around 10mW in Hi freq

- Close/on state (when around 3Vdc applied to the switch controls):
Can pass 6Watt, 25Vac pp @ sub 0.5MHz

- Rds on: up to 200mOhm when switch is on state for minimal loss

- Open/off state (when no any power applied to the switch- normally off):
Can block 25Vac pp @ above 10MHz signal w isolation around 20dB

- Low profile: SMT part, preferably around 1mm height

- Target price: up to 2$ per unit
Click to expand...
 

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