RF High power Amplifiers

[Mabrok]

Hi
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

 

[SLK001]

Hi
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.

 

[Mabrok]

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

 

[eraste]

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

 

[Mabrok]

Thank you
what is about other parameters ? PAE and NF and so on

 

[eraste]

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.

 

[Mabrok]

Class A practically how much PAE?

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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?

 

[SLK001]

Class A practically how much PAE?

- - - Updated - - -

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?

 

[Mabrok]

output power = 30dBm

 

[SLK001]

One watt isn't considered high power. With this power level, any suitable substrate will suffice.

 

[BigBoss]

Class A practically how much PAE?

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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?

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.

 

[Ata_sa16]

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.