Balanced Amplifier Design

[nandy88]

Hi,

I am trying to design a balanced amplifier using RF transistor over the range of frequency. My goal is to obtain a flat gain and P1dB variation of +/- 1dBm across the band. Could you please tell me, is there is any standard technique to achieve these goals?

- - - Updated - - -

Sorry forgot to mention Frequency range.

Freq range: 3 - 3.5 GHz

 

[Ow@i$]

why don't you try ready made amplifiers from minicircuits or else??

 

[nandy88]

It is a part of my project. I have to design the amplifier by my own

 

[BigBoss]

First of all, there is a standard architecture for balanced amplifiers.Using 90 degree hybrid coupler at the input and output is mandatory.2 identical amplifier are connected to these hybrid couplers.
There are many papers and app. notes on the internet.

 

[nandy88]

Hi,

Thanks for your reply.

My problem in the balanced amplifier design are,

1. How to select the optimum impedance for load and source side? Since, I have load and source pull simulation impedance values for each frequency from 3.0 to 3.5 GHz.

2. How to design a Matching network? Any algorithms like SRFT?

3. How to get a flat gain and P1dB over this frequency range?

Please do reply.

 

[BigBoss]

Hi,

Thanks for your reply.

My problem in the balanced amplifier design are,

1. How to select the optimum impedance for load and source side? Since, I have load and source pull simulation impedance values for each frequency from 3.0 to 3.5 GHz.

2. How to design a Matching network? Any algorithms like SRFT?

3. How to get a flat gain and P1dB over this frequency range?

Please do reply.

1-2-Optimum Load Impedance is defined by doing Load Pull simulations for each amplifier.Since you have already defined the optimum impedance,thus you can match this impedance to 50 Ohm by simple LC matching circuit.Because 90 degree hybrid coupler input and output impedances are always 50 Ohm.It shouldn't be very difficult..
3-Obtaining flat frequency response can be obtained either by applying serial feedback or parallel feedback or both.500 MHz is not a very wideband so all you should do is applying an amount of feedback.
Flatness can also be obtained by using proper feedback with tilt function but that can not guarantee this flatness,fedback is better but you take gain dropping into account.

 

[muhammad.usman]

https://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5596226&tag=1

This is some work I did in my bachelors. It was done using amplifier ICs but it will give you idea atleast,

Thanks,
Usman