# RF switch

Discussion in 'Wireless & RF Design' started by raa, Apr 5, 2011.

1. ### raa Thread Starter New Member

Apr 5, 2011
18
0
hi all, iam working on a signal that need modulation, am modulating a pulse and expecting the result as this picture

http://img97.imageshack.us/i/untitl3edn.png/

i will use an RF analog switch IC

it will obtain to me the desired result ,but i have three questions about this RF switch

-the IC band is 4.5Ghz , does it work on low signal freqance cuz the two signals am using is 20 MHz carrier freqancy and 1 KHZ pulse freqancy

-do i need to put a coupling capacitors at the inputs ? , if so what is their values ?

-do i need to put a resistance at the output becuse in the datasheet there is a resistance at the output in the test circuits section.

sry for asking the too much questions but i can't find the answers in the datasheet...any help would be appreciated

2. ### shawnjones New Member

Apr 22, 2011
3
0
The datasheet sheet says that "Isolation is high over the DC to 1 Ghz frequency range" so 20Mhz should be fine. As far as the CTRL frequency, I do see on/off times listed in the specifications. They are listed in nano seconds, there are 1,000,000,000 in one second.

Take the on time and add it to the off time listed, then add the amount of time that you want to switch to be on in nano seconds. If you multiply that total by 1000, and it's less than 1,000,000,000 then the answer is yes, it will work at 1Khz.

Like this:
(On time + Off time + length of pulse in nano seconds) x 1000 = A
If A is <= 1,000,000,000 than this will work fine.

Someone correct me if I'm thinking wrong here, but that is what I would do. As far as the coupling and resistor, let's make sure that this IC will work for you first.

Hope this helps, hope I'm not totally wrong.

Cheers.