wide band IF amplifier design help

[zxl13]

I want to design an amplifier inband is 200-400MHz
now the problem is that if I get the gain flatness in 1dB ,
the inband return loss will be poor.
This is due to most transistor has high gain and poor gain flatness at low frequency in a relative wide band.
Any advice can help me to catch both gain flatness and good RL?

 

[BigBoss]

I want to design an amplifier inband is 200-400MHz
now the problem is that if I get the gain flatness in 1dB ,
the inband return loss will be poor.
This is due to most transistor has high gain and poor gain flatness at low frequency in a relative wide band.
Any advice can help me to catch both gain flatness and good RL?

Use Philips' "Wideband Transistors" with a little bit feedback ( series or parallel or both ).
You have to use a software ( any ) to optimize Input-Output Return Loss and Gain flatness. Take care stability !!
For instance you may easily obtain 15dB Power Gain in that band with BFG93A or similar small signal wideband transistor a little bit feedback.
You can catch +/- 0.3dB flatness with a software optimization.
Feedback will correct flatness and return losses simultaneously.

It's not very difficult..

Good Luck

 

[flatulent]

AdLab contains a good two port analysis program. http://home.t-online.de/home/weberconnect/adlab2.htm is where you download the program. It will run for about 20 times. If you pay the $40 US registration fee the feedback function will be activated. You can the do a little cut and try with the feedback.

This set of programs is well worth the $40.

If you have an analysis program with optimization that program can do it all for you.