Bandwidth boosted stacked memory
A high bandwidth memory system. In some embodiments, the system includes: a memory stack having a plurality of memory dies and eight 128-bit channels; and a logic die, the memory dies being stacked on, and connected to, the logic die; wherein the logic die may be configured to operate a first channel of the 128-bit channels in: a first mode, in which a first 64 bits operate in pseudo-channel mode, and a second 64 bits operate as two 32-bit fine-grain channels, or a second mode, in which the first 64 bits operate as two 32-bit fine-grain channels, and the second 64 bits operate as two 32-bit fine-grain channels.
1. A high bandwidth memory system, comprising:
a memory stack comprising a plurality of memory dies and eight more than two full-width channels; and
a logic die, the memory dies being stacked on, and connected to, the logic die;
wherein the logic die is configured to operate a first channel of the full-width channels in:
a first mode, in which a first half of the full-width channel operates in pseudochannel mode, and a second half of the full-width channel operates as two quarter-width fine-grain channels, or
a second mode, in which the first half of the full-width channel operates as two quarter-width fine-grain channels, and the second half of the full-width channel operates as two quarter-width fine-grain channels.
2. The high bandwidth memory system of claim 1 , wherein:
the logic die is configured to operate the first channel in the first mode, and a second channel of the full-width channels in the second mode.
3. The high bandwidth memory system of claim 1 , wherein:
the logic die is capable of changing, at run time, the first channel from operating in the first mode to operating in the second mode.
4. The high bandwidth memory system of claim 3 , wherein:
a mode of the first channel is configured to be controlled at run time via a mode register of the first channel.
5. The high bandwidth memory system of claim 3 , wherein:
a mode of the first channel is configured to be controlled at run time via a reserved-for-future-use pin.
6. The high bandwidth memory system of claim 1 , wherein:
the logic die is further configured to operate the first channel in the first mode, with a burst length of 2 for the first half of the full-width channel.
7. The high bandwidth memory system of claim 1 , wherein:
the logic die is further configured to operate the first channel in the second mode, with a burst length of 2 for a first fine-grain channel of the quarter-width fine-grain channels.
8. The high bandwidth memory system of claim 1 , wherein:
the full-width channels have a width of 128 bits.
9. A high bandwidth memory system, comprising:
a plurality of stacked memory dies,
more than two channels, and
a logic die,
the stacked memory dies being stacked on, and connected to, the logic die;
each memory die comprising a plurality of banks each comprising a plurality of rows and a plurality of columns;
a first channel of the eight channels being configured to be operable as any one of: a single full-width channel, two half-width pseudo channels,
a half-width pseudo channel and two quarter-width fine-grain channels, or four quarter-width fine-grain channels;
wherein the logic die can be configured to return a burst of data following a data access at a row of the rows and a column of the columns within the plurality of banks associated with the first channel, the burst of data having a burst length less than a burst length corresponding to a 256 bit transaction.
10. The high bandwidth memory system of claim 9 , wherein the logic die is configured to operate the first channel as two half-width pseudo channels with a burst length of less than 4.
11. The high bandwidth memory system of claim 9 , wherein the logic die is configured to operate the first channel as four quarter-width fine-grain channels with a burst length of 2 or less.
12. The high bandwidth memory system of claim 9 , wherein the logic die is configured to use a reserved-for-future-use pin to receive a signal indicating the burst length to be returned.
13. The high bandwidth memory system of claim 9 , wherein the logic die is configured to receive a signal indicating the burst length from a host processor.
14. The high bandwidth memory system of claim 13 , wherein the host processor is a central processing unit.
15. The high bandwidth memory system of claim 13 , wherein the host processor is a graphics processing unit.