12ghz power amplifier

I am going to do a power amp design at 12GHz with the gain of 30dB and the Pout, 1 dB is 30dBm. Currently I have 4 stage of the transistors in order to acheieve the required gain. However, I am not sure how to do the circuit biasing from ADS......Can anyone help,plz?

I suggest you select Avago,Hittite or UMS chipset.

Thanks, but I need the ADS model. I will use the ADS component library to do the simulation. Currently I found around 4 components of transistors but I would like to know how to achieve the Pout1db at 30dBm, 12GHz? Do you have any idea I can find such kind of transistor in ADS?

In ADS there is basical model, I suggest you to find a transistor model on Manufacturers web sites and set up the design kit in ADS;

unfortunately I don't know provider at 12GHz band, but by searching in google you could find easily.

In my opinion, to achieve 30dBm at 12GHz by using discrete components will be very difficult task.Even tough the proper components have been found, implementation such circuit on a PCB will be very tedious optimization process.Especially measurments wil be very tough..
When you loook around the semiconductors suppliers, you will see that some MMIC's have been developed for this purpose because of their monolithic structures that provide easier design and optimization.
By anyway, it doesn't mean that is not realizable but really hard to do..

In my opinion：you can use the s-parameters to design in ADS,

I don't think it is a big deal to design a 1 Watt 12GHz power amplifier, since you choose the right transistor's lineup.
The first thing to regard is to select the transistors with the input pre-matched. This fact will make easy the circuit design as the most problematic step in any PA's amplifier design is the input matching circuit.
The output transformer should be designed, as usual, regarding the required power level. The load line approach described in the Cripps book is the most suitable for this.
You haven't mentioned what is the desirable bandwidth of your amplifier, but you can consult, for example, Excelics web site at http://www.excelics.com/ where you can find several power fets with input pre-matched for 12GHz in a broad range of output power.

NandoPG

I don't think I can deal with a 4 stage PA at such high freq. the port impedance matching and mutual effects between the stages may be very complicated.

Maybe you can try less stage but the power combination.

The 3 to 4 stage transistors can achieve the required gain but the problem is Pout 1 dB point at 30db gain. Most available transistor model in ADS cannot full fill this. I was suggested to use the power combiner in this application.

Yes you are right.
What transistors that are selected by you?
What is the final transistor?
Will the combiner is 2to 1 or 4 to 1?
Basically you need to do some budget analysis accounting the losses like in combiner etc.

As I mentioned before, Excelics has a brod range of choices for pre-matched power devices in 12GHz. Please have a look on www.excelics.com for details.

I also, don't think you will need to use any dividir/spliter in your amplifier.

NandoPG

Thanks for your suggestion. Actually I understand you point. However, the transistor model can't be found in ADS but we have to show our simulation to our Prof. That's the only choice for me.

If this is just for academic purpose, you can find in Excelics's web site a lot of devices characteized by a Curtice-cubic model. Also in the web site you can find the linear model for the packages.

So the whole thing is: you pick the model of the transistor's chip that fits in your application. For that search in High Efficiency Heterojunctions Power FET and then in Application Info to download the table with the Curtice's parameters.

Then do the embedding of the chip's nonlinear model with the package of your choice. Package models can also be found in Application Info for downloading.

Having this, you can do your design and all sort of non-linear simulations.

Of course you can put more time to get a working amplifier, since the models are pretty precise.

Give it a try.

NandoPG

need some papers about RF PA linearization

Added after 34 seconds:

[1] J. Yi, Y. Yang, M. Park, W. Kang and B. Kim, Analog predistortion Linearizer for High Power RF Amplifiers, IEEE Transactions on Microwave Theory and Techniques, vol. 48, no.12, Dec. 2000.

Added after 23 seconds:

[2] T. Nojima and T.Konno, Cuber Predistortion Linearizer for Relay Equipment in the 800 MHz Band Land Mobile Telephone System, IEEE Transactions on Vehicular Technology, vol. VT-34, pp.169-177, Nov 1985.

Added after 15 seconds:

[3] T. Rahkonen, T. Kankaala, M. Neitola and A. Heiskanen, Using Analog Predistortion for Linearizing Class A-C Power Amplifiers, Analog Integrated Circuits and Signal Processing, 22, pp. 31-39,1999.

Added after 58 seconds:

[4] A.N. Andrea, V. Lottici and R. Reggiannini, RF Power Amplifier Linearization through Amplitude and Phase Predistortion, IEEE Transactions on Communications, vol. 44, Nov 1996, pp.1477-1484.

your paper requirements "Analog predistortion Linearizer for High Power RF Amplifiers, IEEE Transactions on Microwave Theory and Techniques, vol. 48, no.12, Dec. 2000."