If i'm understanding this correctly, you only consider a miller capacitance to be a capacitor multiplier circuit( capacitor across input to output). The bjt filters merely let you design for lower currents, and thus you can make r smaller without making the capacitor larger. Essentially you can move your pole into higher frequencies without needed a larger capacitor. The misconception being this effect does not actually increase capacitance in any way.
Thanks for your comments. There are other cap multiplier circuits that entail current amplification rather than voltage amplification (like base to emitter in BJT).
Well, it is not related to filtering, but low output impedance is a fairly important aspect of any power supply and this circuit enables it due to the common-collector configuration of the BJT. Nevertheless, no doubt that there is a huge misconception about the statements given in the Cadence presentation. Suggestion to all electrical engineers - please use relevant references to learn electronics (Sedra-Smith, Gray-Meyer, etc). Thanks for a nice video lecture!
Companies like Cadence and Altium should stay away from this kind of presentations on subjects they don't fully understand. It would be better if they would both concentrate on delivering quality software. Cadence used to be good. But not so for the latest versions they released. Altium is an other story.
Do you have a suggestion for alternative circuits that filter that noise? I feel that it is especially important for suppressing 60hz ripple without having massive capacitors to charge
Ive used this circuit to remove a very small ripple on a 200V DC Supply. I needed to have a very clean output voltage and the load was minimal because it was for a supply for a sensor. What would you recommend instead in this case? I have to say it was a really good solution because it was easy, small and power used was minimal because of low current.
13:21 I guess a solution is to combine a normal RC filter with small R to cut high frequencies with the RC+BJT (with higher R) to deal with lower ones (so you don't need a huge C)
@@sambenyaakov unfortunately yes. That's why you have to use a small R and can't filter low frequencies unless you have a ridiculously big capacitor. But that's OK if that tasks is done by the BJT+RC.
Thank you for the great informations can you please makes a lecture about capacitor control circuit with dual mosfet for resonance maintaining circuits
Thanks for your input. Indeed you can, but better to add resistance to Rf to get a lower frequency break point. On the other hand , if the current drops you may still not have a sufficient voltage drop with the Rf.
