up converting 433MHZ ISM band ICs to non-ISM band?!

[7rots51]

hello

suppose I want to design a transciever in non ISM band of 1600MHZ ,can I use 433 MHZ ISM band ICs and mixer+PLL+VCO+ PA to upconvert TX part to 1600MHZ.

and by adding LNA + filter+ mixer+pll+vco downconvert RX section(1600MHZ) to 433MHZ , and all other tasks is done in ISM band IC at 433MHZ?

Is this practical? is this a good way?
Is there any disadvantage in this method?

 

[RFDave]

Hi

That's possible to do. I can't answer if that is a good way to do it though. How many are you intending to build? 1600 MHz is pretty close to the GPS bands, do you have a license to use that band? The disadvantages are that your performance is restricted to the ISM band data rates and bandwidths. I'd consider it a kludge that is good for one or two, but nothing more than that.

Dave

 

[biff44]

Agree there! It is hard to take a chip designed to just squeek by some emissions requirements at one band and upconvert it to another band. At the least, you are going to have to do some additional filtering, step size reformating, and modulation reprogramming. For example, what is a good modulation bandwidth at 433 might be too small a bandwidth at 1600.

I would start by getting the 433 chip on a protoboard and hook it to a spectrum analyzer and pretend it is working at 1600, and see if it will meet the specs. Will the 2nd/3rd harmonic upconvert to a band you do not want to interfer with?

Also, if it is a low power chip, upconverting and amplifying to a higher power might bring on much more stringent specs to meet--ones the original chip is 20 dB out of spec for!