Glossary comparison
DDR PHY vs Memory controller: what is the difference?
The difference
The memory controller is the digital logic that schedules requests, refreshes the DRAM and manages power states. The PHY handles the electrical signalling and timing at the pins; the two talk through DFI.
The PHY is the mixed-signal block that drives and samples the pins, handles training and meets signal timing. The controller is the digital logic that decides which commands to send and when.
The two terms
DDR PHY
The analogue and timing block that drives a DRAM's parallel command, address and data buses, handling per-bit deskew, on-die termination, drive strength calibration and the training sequences that centre timing.
Memory controller
The logic block that turns processor or accelerator requests into DRAM commands, scheduling activates, reads, writes, refreshes and power states across banks and ranks.
Side by side
| Field | DDR PHY | Memory controller |
|---|---|---|
| Stands for | Double Data Rate Physical Interface | Not an abbreviation |
| Type | Term | Component |
| Domain | Interfaces & SerDes | Memory & Storage |
| Group | Memory interface | Memory interface |