two questions - difference : passive filter and active filt

[lhlbluesky]

two questions need help

1\ what is the difference of passive filter and active filter ? for the difference, what aspects should be considered?

2\what is deep-nwell technology? and what's the purpose of deep-nwell?

pls help me.

 

[LvW]

Re: two questions need help

to 1.) passive filters contain no amplifiers; for pole Q´s larger than 0.5 (good selectivity), coils (inductances) are required. As coils have bad properties (heavy, expensive, radiating, EMC-sensitive,..) their function can be replaced by specific amplifier arrangements. That are actice filters.

 

[sriramachandra]

Re: two questions need help

Passive filter will have only R and C's and Active will have Gain associated with them and are implemented with opamps..........

 

[LvW]

Re: two questions need help

Passive filter will have only R and C's and Active will have Gain associated with them and are implemented with opamps..........

In many cases, passive filters contain also coils (inductances).
Active filters can be implemented with opamps or OTA´s or Current Conveyors or suitable combinations; active filters have NOT always gain associated with them.
In some cases active elements are used simply to simulate the behaviour of inductances in standard passive ladder structures.