RF Amplifier Usage Question

Question

Hello All,

I am developing an extremely high frequency RF Transmitter solution and I am confused about the workings of RF Amplifiers.

At the moment I am specifically looking at this transmitter and this amplifier.

I have two questions:

If I were to apply this in a custom PCB (where the transmitter takes Digital input, converting to an RF Signal, taking that output to the amplifier, which in turn puts it through to an antenna), are these the correct parts for the respective jobs?
Is the output of the Transmitter and output of the Amplifier a co-axial type plug? If not, what is the correct type?

waelect · Accepted Answer

Hi Joshua,

I will have to agree with most of the other comments here as well. The 2 devices just from their titles will not work as the Tx chip is 2.4GHz and the amplifier starts at 6GHz well above the 2.4GHz of the transmitter. Definitely a specialized area is PCB design too as there is a lot of stray capacitance's and Inductance's that are involved in this type of design.

There are plenty of specialized module that can be purchases from places, one being mini-circuits and even on element14/Newark http://uk.farnell.com/jsp/search/browse.jsp?N=2031+203582&Ntk=gensearch&Ntt=rf+module&Ntx=mode+matchallpartial

As a radio technician I too am learning as I progress through University to finer details of high frequencies in PCB design. I think there is a certain amount of secrecy in the question ie not divulging the idea but maybe more specifics are needed in what you are trying to accomplish.

As far as the general questions, 2) coax connectors are an option but so are PCB design antenna which are also plausible. As long as you have the correct impedance matching (usually 50ohm ) it should work OK either way.

The first question is mute point, you will need to use a different amplifier completely to work with the transmitter.

Malcolm

michaelkellett · Answer

@ Joshua, it's not a matter of trying to put you down but save you from falling down a deep dark hole. Your original question was very much phrased to suggest that you were trying to build something specific. In the olden days people learned about RF mainly via amateur radio - this doesn't seem so popular or accessible now . You could start by looking at data sheets and app notes for the license exempt low power radio chips from TI, Microchip and Atmel. There is a lot of helpful material there. These parts will work at 455MHz or 900 ish MHz. These are still very high frequencies to start with and the theoretical design of circuits and board layouts very, very difficult. Most engineers use a combination of the theoretical and the empirical (which requires the fancy test gear). You can find some suggested board layouts in app notes an these will probably work if followed very carefully. You will get an idea of some of the issues involved in the design. (Try here to start with looking at TI stuff: Sub-1 GHz - Overview - TI.com ) The highest frequencies at which I've done any paid work in RF (rather than digital which is different) is designing and testing aerials for Mifare which is ony 13.5MHz - and that can get quite tricky. I've used modules that work at much higher frequencies but that doesn't count. MK