jianke
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Recently I met an interesting question for RF amplifier design. As we know, by adding a series inductor at Emitter, we can increase the stability of a BJT Common-Emitter (CE) amplifier. When it comes to a Common-Base (CB) or a Common-Collector (CC) amplifier, what should we do to increase its stability?
My objective is at 2.14GHz: (1) the CB amplifier works as a “current follower” (voltage amplification); (2) the CC amplifier works as a “voltage follower” (current amplification).
What I have tried for a CB amplifier is: (1) Adding a series resistor at output, but the S parameters becomes really bad, typically S11 and S22. Also, the voltage gain decreases much. (2) Using the ADS optimization tool to improve stability and S-parameters performance, but the results are not good. Typically the CB amplifier cannot work as a “current follower”. Also, the voltage gain decreases much.
The attachments are ADS simulations files and some simulations results. I hope they would be useful for your analysis. Thanks!
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