High bandwidth memory interface
This invention describes an improved high bandwidth chip-to-chip interface for memory devices, which is capable of operating at higher speeds, while maintaining error free data transmission, consuming lower power, and supporting more load. Accordingly, the invention provides a memory subsystem comprising at least two semiconductor devices; a main bus containing a plurality of bus lines for carrying substantially all data and command information needed by the devices, the semiconductor devices including at least one memory device connected in parallel to the bus; the bus lines including respective row command lines and column command lines; a clock generator for coupling to a clock line, the devices including clock inputs for coupling to the clock line; and the devices including programmable delay elements coupled to the clock inputs to delay the clock edges for setting an input data sampling time of the memory device.
1. A Dynamic Random Access Memory (DRAM) controller configured for communication with at least one semiconductor device over an interface, the controller comprising:
a) data terminals for coupling to the interface and for providing data signals for transmission to the semiconductor device;
b) at least one data clock terminal for coupling to the interface and for providing at least one data clock signal for transmission to the semiconductor device;
c) output drivers for driving said data signals and said at least one data clock signal on said data terminals and said data clock terminal, respectively; and
d) polysilicon termination resistors coupled to each of said data and data clock terminals, and said polysilicon termination resistors are within said DRAM controller and integrated with said DRAM controller on a semiconductor chip.
2. The DRAM controller as claimed in claim 1 wherein said polysilicon termination resistors are series stub termination resistors.
3. The DRAM controller as claimed in claim 1 wherein said at least one data clock terminal is a pair of terminals.
4. The DRAM controller as claimed in claim 3 wherein said at least one data clock signal is two clock signals.
5. The DRAM controller as claimed in claim 4 wherein a selected one of said data clock terminals is driven during a particular write operation.
6. The DRAM controller as claimed in claim 1 wherein said at least one data clock signal is driven aperiodically.
7. The DRAM controller as claimed in claim 6 wherein said at least one aperiodically driven data clock signal is preceded by a preamble.
8. The DRAM controller as claimed in claim 7 wherein said preamble begins with an interval held to a low logic level for more than a one bit interval.
9. The DRAM controller as claimed in claim 8 wherein said preamble consists of the bit pattern ‘0001’.
10. The DRAM controller as claimed in claim 1 wherein said at least one data clock signal is a source synchronous data clock signal.
11. The DRAM controller as claimed in claim 1 wherein said data terminals and said at least one data clock terminal are bidirectional terminals.
12. The DRAM controller as claimed in claim 1 wherein a data rate of said data signals is double data rate.
13. A Dynamic Random Access Memory (DRAM) system comprising:
a) at least one DRAM including polysilicon termination resistors within said DRAM and integrated with said DRAM on a semiconductor chip;
b) a DRAM controller; and
c) a data bus having said polysilicon termination resistors coupled to it, said data bus for providing write data from said DRAM controller to said DRAM, and for providing read data from said DRAM to said DRAM controller.
14. The DRAM system as claimed in claim 13 wherein said DRAM further includes push-pull output drivers enabling device application of said read data to said data bus.
15. The DRAM system as claimed in claim 14 further comprising at least two power supplies electrically connected to said push-pull output drivers.
16. The DRAM system as claimed in claim 13 wherein said polysilicon termination resistors are series stub termination resistors.
17. The DRAM system as claimed in claim 13 wherein said data bus includes at least one data clock line.
18. The DRAM system as claimed in claim 17 wherein said at least one data clock line is driven aperiodically.
19. The DRAM system as claimed in claim 13 wherein said at least one data clock line is a source synchronous data clock line.
20. The DRAM system as claimed in claim 13 wherein said at least one data clock line is a pair of data clock lines.
21. The DRAM system as claimed in claim 20 wherein a selected one of said pair of data clock lines is driven during a particular data transfer operation.
22. The DRAM system as claimed in claim 13 wherein the clock signal on said at least one data clock line is preceded by a preamble.
23. The DRAM system as claimed in claim 22 wherein said preamble begins with an interval held to a low logic level for more than a one bit interval.
24. The DRAM system as claimed in claim 22 wherein said preamble consists of the bit pattern ‘0001’.
25. The DRAM system as claimed in claim 13 wherein said data bus is configured to carry Double Data Rate (DDR) data signals.
26. A Dynamic Random Access Memory (DRAM) comprising:
a) a first terminal for coupling to a clock line;
b) a plurality of second terminals for coupling to a command bus providing address and control information to the DRAM, said clock line and said command bus comprising a source synchronous bus;
c) polysilicon termination resistors coupled to said plurality of second terminals, and said polysilicon termination resistors are within the DRAM and integrated with the DRAM on a single chip.
27. The DRAM as claimed in claim 26 , further including at least one third terminal for coupling to at least one data clock line that is driven aperiodically.
28. The DRAM as claimed in claim 26 wherein said polysilicon termination resistors are series stub termination resistors.
29. In a memory controller, a method for synchronization comprising:
a) employing polysilicon resistors integrated with the memory controller on a semiconductor chip to resistively terminate data bus terminals and data clock terminals of the memory controller;
b) receiving data clock signals on said data clock terminals;
c) generating a data sampling clock with said received data clock signals;
d) receiving read data signals on said data bus terminals; and
e) sampling the received read data signals with said data sampling clock so that the data input to the device is synchronized with the data clock signals.
30. The method as claimed in claim 29 wherein the memory controller is a Dynamic Random Access Memory (DRAM) controller.
31. The method as claimed in claim 30 wherein said resistively terminating said data bus terminals and said data clock terminals is accomplished with a series stub termination resistor.
32. The method as claimed in claim 29 wherein said data clock signals is two clock signals.
33. The method as claimed in claim 32 wherein a selected one of said two clock signals generates said data sampling clock for a particular read operation.
34. The method as claimed in claim 29 wherein said data clock terminals is a pair of terminals.
35. The method as claimed in claim 34 wherein said clock signals are delayed through programmable delay circuits to generate said data sampling clock.
36. The method as claimed in claim 29 wherein said data clock signals are aperiodic data clock signals.
37. The method as claimed in claim 36 wherein said aperiodic data clock signals are preceded by a preamble.
38. The method as claimed in claim 37 wherein said preamble begins with an interval held to a low logic level for more than a one bit interval.
39. The method as claimed in claim 38 wherein said preamble consists of the bit pattern ‘0001’.
40. The method as claimed in claim 29 wherein said write data signals are Double Data Rate (DDR) signals.
41. The method as claimed in claim 29 wherein said data clock signals are source synchronous data clock signals.
42. The method as claimed in claim 29 wherein said data bus terminals and said data clock terminals are bidirectional terminals.