David_
Advanced Member level 2
Hello.
I am trying to design a linear regulator stage following a switching step-down regulator, in a application note from Linear Technology the "secret sauce" is ferrite beads before and after the linear regulator each with its own capacitor.
But when I go to digikey to select a bead I find something that makes me quite unsure, I can get a bead that can handle the current in my circuit that presents a impedance of 100Ω at 100MHz, actually there are several but if I am willing to pay a little more(or 2* more) I can get a bead that presents 800Ω at 100MHz.
When the signal of interest is low frequency, is the higher the impedance at higher frequency's the better?
- - - Updated - - -
If you look at these two beads, the price differ much but so does the impedance at 100MHz.
Is it worth paying more in a case such as this?
https://www.digikey.se/product-detail/en/28F0181-1SR-10/240-2511-1-ND/1015953
https://www.digikey.se/product-detail/en/HR2220V801R-10/240-2433-1-ND/806793
I am trying to design a linear regulator stage following a switching step-down regulator, in a application note from Linear Technology the "secret sauce" is ferrite beads before and after the linear regulator each with its own capacitor.
But when I go to digikey to select a bead I find something that makes me quite unsure, I can get a bead that can handle the current in my circuit that presents a impedance of 100Ω at 100MHz, actually there are several but if I am willing to pay a little more(or 2* more) I can get a bead that presents 800Ω at 100MHz.
When the signal of interest is low frequency, is the higher the impedance at higher frequency's the better?
- - - Updated - - -
If you look at these two beads, the price differ much but so does the impedance at 100MHz.
Is it worth paying more in a case such as this?
https://www.digikey.se/product-detail/en/28F0181-1SR-10/240-2511-1-ND/1015953
https://www.digikey.se/product-detail/en/HR2220V801R-10/240-2433-1-ND/806793