Which topology is the best for RF design?

[eda_range]

Take a look at this pic,
please tell me which one is better for RF design and why?

thank you.

 

[safwatirteza]

Re: topology choice

These both circuits are practical examples of a differential amplifiers. Normally these kind of topologies are known as Long-Tail Pair topology. You need these type of circuits to amplify very small differences between two input signals. One on the right provides fixed gain. On the left has transistors and can provide higher gain at variable frequency. It is more robust i think at RF frequencies if suitable transistors are selected.

I hope i helped and made sense

 

[eda_range]

topology choice

thanks for your help.
Could you explain more specifically why the left one provide higher gain at variable freq?

 

[safwatirteza]

Re: topology choice

As far as i know with transistors you can easily get current gain and providing higher current at collector will be better for amplification purposes.