AC COUPLING RESISTORS ON DDR TERMINATION RAIL

P

pacman22

Junior Member level 1
Joined
Oct 11, 2022
Messages
16
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
158
Hey!

This is a schematic of DDR3. I observed that the termination voltage rail VTT (0.65V) is coupled to VDD_DDR (1.35V).
What purpose does it serve, is it really required? Also, there are multiple capacitors, can they be replace by one equivalent capacitor?
 

Sort by date Sort by votes
A better title would be "VTT bypass capacitors" rather than "AC coupling resistors".

It's generally reguired to have multiple bypass capacitors for VTT net as well for supply voltages to create low impedance rails. Usually all bypass capacitors are referenced to GND, don't know why they used VDD instead. Possibly VDD near VTT copper pour.
 

Upvote 0 Downvote
You must log in or register to reply here.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…