voltage amplifier before PA

Hello,

I'm implementing class E PA.I have 20mv(peak to peak) signal.First,I want to increase the strength of the signal to 1V(peak to peak).So I need an Voltage amplifier before PA.

Can you suggest a low power voltage amplifier operating at 4GHZ frequency.


Thanks in advance,

Regards,
Praveen.

Why not run your signal into a 50 ohm resistor in shunt to ground, then use a good-old 50 ohm in/out matched gain block amplifier? 20 mVpp is -60 dBm, and 1 Vpp is -26 dBm. That's 34 dB of gain... maybe you'll need two smaller gain blocks to accomplish that step up. However, -26 dBm is very small power, so you can easily find parts that will get you there. Look at places like Mini-Circuits, then Sirenza, Motorola, Triquint, M/A-COM, etc... PA vendors.

Thankyou for the info.I'm implementing the design with cadence bicmos8hp.

I have one more question.Do I need to consider the power dissipation of this voltage amplifier while calculating efficiency of the power amplifier.

If I consider this amplifier in the efficiency then it efficiency of total design is dropping below 50 %.How can I improve efficiency of PA?.


Regards,
Praveen

Ideally for efficiency calculation is to use PAE (Power Added Efficiency) = (Pout_watt - Pinp_watt) / (Total_DC_Power_watt)
Meantime the power consumption of the gain amplifier is much lower than PA power consumption, and could be ignored when calculating the total efficiency.

You better add 30 dB to the value because dBm is dB relative to 1 mW not 1W. 34 dB gain is still correct.

As I'm using MOSFET in the design can I ignore Pinp_watt (i/p current = 0) while calculatin efficiency?.

Dear praveen450
Hi
As i know , it is usual , that we use the class C amplifiers as , drivers for class E amplifiers. Or you can use one GALI-5
. It is a kind of driver , for all of the RF amplifiers, that can work at frequencies , up to 6GHZ as well as .
Best Wishes
Goldsmith

Hello,

Thankyou for the information.

As I'm implementing the circuit in cadence bicmos8hp process I think I cant use GALI-5 circuit.Is it true?.

If I use class C amplifiers as drivers it decreases the efficiency a lot because the class E amplifier is dissipating 500mW of power.

Please let me know whether I'm goin in a right direction.

Thanks in advance,

Regards,
Praveen

Dear praveen
How much is the out put power of your class E stage? . I think this value of loss power is so high for a class E . what are the value of your components? is your class E stage , single ended? or is that a double ended class E amplifier?
Regards
Goldsmith

Hi,

I'm sorry.The output power is 500mW not the dissipated power.

The MOSFET is 300um/160nm and output is tuned to 1.5GHZ with matching circuit.

Regards,
Praveen

Again Hi
But as you said at your first post , you want 4GHZ frequency?!
though your out put power is 500mw , but i can not understand that why you don't want a limited class C amplifier as a driver . if you try to limit it , you can achieve the agreeable efficiency.it is the usual method that i said . and you can see it at some of professional designs .
By the way , if your frequency is not about 4 GHZ , and if that is about 1.5GHZ your design will be more simpler .
Respectfully
Goldsmith