- Joined Sep 17, 2011
Would a folded cascode amplifier be better at reducing the miller effect or would a simple nmos cascode be better?
This doesn't make sense to me. In neither case is either transistor in common collector mode.In the cascode output transistor, capacitive current resulting from the miller capacitance is shunted to common at the base in the common base connection. The drive transistor, if common emitter operates at a constant Vce so it has no miller capacitance, but it has significant voltage gain. If the drive transistor is the opposite polarity as in a folded cascode, it operates in the common collector mode thus has a voltage gain of unity and has the potential of wider bandwidth.
That's my take on it. Other members might be able to dispute this, or add to it.So, your implying that, the miller effect is reduced the same whether it's cascode or folded cascode given the same performance of the transistors and the only advantage of nmos is that it has better frequency characteristics than pmos. But a folded cascode will need less voltage between the rails..am i reading u right?
who know this question,please tell me. thank youall i really know is that the input capacitance increases if the circuit for the input signal has a high output impedance and cascodes reduce this because the input and output are isolated from each other.. right? but how can different cascodes types differ from each other? will the folded cascode be better at reducing the miller effect because the input and output stages have more differing characteristics?
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by Aaron Carman
by Jake Hertz