RF High power Amplifiers
In designing of RF power Amplifiers, the setting of specifications ( Gain, NF, PAE, and so on) will be based on what?
Anyone have an idea?
TQ
Usually, these parameters are specified in the design criteria. NF generally doesn't apply to power amps.
Thank you for replying
But, I meant how to set this specification based on what? Is it on the transistor used?
I am going to do master project and my topic is designing RF power Amplifier for S-band 2 to 4GHz, so I need to set goals (specifications for the design)
How should be setting?
TQ
Hi,
For maximum power : the criterion is the matching to the load and source charge.
For bandwidth : you must check that the amplifier is stable on whole bandwidth and beyond, that is matched too and that the gain is almost constant.
Bye
Thank you
what is about other parameters ? PAE and NF and so on
For PAE :
In fact, it depend on the class of you amplifier.
Class B , class C or class AB.
For the Noise as we have previously said : the noise is not taken into account for a power amplifier.
In fact for an amplifier, if you choose to minimize the noise, the gain will not be maximum and vice-versa.
Class A practically how much PAE?
For RF high power Amplifier for S-band 2 to 4 GH, Anyone has an idea about the best substrate can be used in the design?
To design for Class A high power would be silly. PAE maxes at 25% for Class A.
For substrate, it depends on your design goals. What is the output power?
output power = 30dBm
One watt isn't considered high power. With this power level, any suitable substrate will suffice.
Class-A Power Amplifiers have theoretically %50 Drain/Collector Power Efficiency ( not PAE ! ) and it can be between practically %20-%40.
Substrate choice is dependent on your circuit design.Of course cost should be considered.Rogers substrates can be used for S-Band even high quality FR can be used.
Gain : you are considering a power gain which is Pout/Pin and it depends on your class. In class A you can get high power but in AB and C power is lower but efficieny is better. generally it is 30 dBm.
NF: noise figure is not important for PA since we are dealing with large signal
PAE: Power added efficieny which is (pout-pin)/pdiss is max for switched power amplifiers ( E, F, J ...). like 50-60% but for class A is minimum like 25%. The problem is they are not fast and they don't work in high frequencies.
Compression point is also important that you have to consider.