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Is there a negative miller effect?

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1mace1

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Assume we have a common gate amplifier and we have a capacitor CC between the input (Source) and the output (drain). Do we see then a negative miller effect on the input?
Because the gain of the common gate amplifier is gmRL and the miller effect on the input is CC*(1-Av). Thus we get approximately -CC*gmRL. That would mean that we now have a RHP pole which introduces +90 degree of phaseshift. Is this right?
Because normally such negative miller effect is used with a low gain amplifier respectively buffers to lower the capacitance on the input.

Hope anyone can help me.
 

Yes - such a capacitor between C and E in common-B configuration provides positive feedback and, thus, increases the input impedance for rising frequencies.
This can be also described by the term "invers (negative) MILLER effect". However, at the same time, the gain decreases (C parallel to Rc).
Why do you expect an RHP pole?

- - - Updated - - -

Update: The capacitor between C and E provides positive feedback only in case of an emitter resistor RE (DC/AC negative feedback) - otherwise the positive feedback signal is shorted by the signal source.
 
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    1mace1

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I thought about such a structure (see link below). Where the second stage is a non inverting amplifier such as a cg-amplifier.
Due to the positive amplifier I would suggest the pole at the input of amplifier 2 is: 1/(Ro1*-(Av2*CC)) where Av2 is gm2*Ro2. Because of this negativ cpacitance on the input the overall pole introduces +90° phaseshift ? And also a left half plane zero is introduced which is approximately gm2/Cc is this right?


https://obrazki.elektroda.pl/2010107600_1472124017.jpg
 

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