Memory with serial input/output terminals for address and data and method therefor
View Patent ↗A memory ( 10 ) has a plurality of memory cells, a transceiver ( 56 ) for receiving a low voltage high frequency differential address signal, and a serial input/output data port ( 52, 54 ) for receiving a high frequency low voltage differential data signal. The memory ( 10 ) can operate in one of two different modes, a normal mode and a cache line mode. In cache line mode, the memory can access an entire cache line from a single address. A fully hidden refresh mode allows for timely refresh operations while operating in cache line mode. Data is scored in the memory array ( 14 ) by interleaving in multiple sub-arrays ( 15, 17 ). During a hidden refresh mode of operation, one sub-array ( 15 ) is accessed while another sub-array ( 17 ) is refreshed. Two or more of the memories ( 10 ) may be chained together to provide a high speed low power memory system.
1. A memory on an integrated circuit, comprising:
an array of addressable memory cells;
a first address input terminal of a transceiver on the integrated circuit for receiving a plurality of low voltage differential serial address input signals for accessing a memory cell of the memory array; and
a first data input/output terminal of the transceiver on the integrated circuit for receiving or providing a plurality of low voltage differential serial data input/output signals based on the plurality of low voltage differential serial address input signals.
2. The memory of claim 1 , wherein said memory is a dynamic random access memory (DRAM).
3. The memory of claim 1 , wherein at least one of said plurality of low voltage differential serial data input/output signals, and said plurality of low voltage differential address input signals are provided at a data rate of at least 2 gigabits per second.
4. The memory of claim 1 , further comprising a clock buffer coupled to the memory for receiving a reference clock signal.
5. The memory of claim 1 , further comprising an address output terminal of the transceiver on the integrated circuit coupled to the first address input terminal of the transceiver on the integrated circuit, the address output terminal of the transceiver on the integrated circuit for providing the plurality of low voltage differential address input signals to access a second memory array.
6. The memory of claim 5 , further comprising a second data input/output terminal of the transceiver on the integrated circuit coupled to said first data input/output terminal of the transceiver on the integrated circuit, wherein said second data input/output terminal of the transceiver on the integrated circuit is for coupling to the second memory array.
7. The memory of claim 1 , wherein said plurality of low voltage differential serial address input signals have a voltage within a range of about 200 millivolts to about 300 millivolts and said plurality of low voltage differential data input/output signals have a voltage within a range of about 200 millivolts to about 300 millivolts.
8. The memory of claim 1 , further comprising a phase-locked loop (PLL), the PLL being locked to predetermined bits of the plurality of low voltage differential data input/output signals to generate a clock signal for timing operation of the memory.
9. The memory of claim 1 , wherein the plurality of low voltage differential serial address input signals are provided to the memory in the form of packets, each of the packets having a start bit, address bits, an end bit, and one or more control bits.
10. The memory of claim 1 , wherein the data input/output terminal of the transceiver on the integrated circuit is adapted to be configured as a multiplexed serial bus terminal for transmitting both serial data signals and serial address signals on a time slotted basis by setting a control register bit.
11. The memory of claim 1 , wherein the data input/output terminal of the transceiver on the integrated circuit is configured to receive a first address signal multiplexed with a second data signal.
12. A memory system, comprising:
a first memory, said first memory comprising:
a first address input port of a first transceiver for receiving a first differential serial address input signal;
a first address output port of the first transceiver for providing a first differential serial address output signal;
a first data input/output port of the first transceiver, wherein, based on a control portion and a chip address portion of said first differential serial address input signal, said first data input/output port of the first transceiver receives a first differential serial data input signal or said first data input/output port of the first transceiver provides a first differential serial data output signal;
a second data input/output port of the first transceiver; and
a second memory coupled to said first memory, said second memory comprising:
a second address input port of a second transceiver coupled to said first address output port of the first transceiver of said first memory;
a third data input/output port of the second transceiver coupled to said first data input/output port of the first transceiver of said first memory, wherein said third data input/output port of the second transceiver of said second memory receives said first differential serial address output signal from said first memory, and, based on the control portion and the chip address portion of said first differential serial address output signal, said third data input/output port of the second transceiver of said second memory provides a second differential serial data input signal to said second data input/output port of the first transceiver of said first memory or said third data input/output port of the second transceiver of said second memory receives a second differential serial data output signal from said second data input/output port of the first transceiver of said first memory.
13. The memory system of claim 12 , wherein said first memory is a dynamic random access memory (DRAM) and said second memory is a dynamic random access memory (DRAM).
14. The memory system of claim 12 , wherein at least one of said first differential serial data input signal of said first memory, said first differential serial data output signal of said first memory, said second differential serial data input signal, and second differential serial data output signal has a data rate of at least 2 gigabits per second.
15. The memory system of claim 12 , wherein said first differential serial address input signal, said first differential serial address output signal, said first differential serial data input signal of said first memory, said first differential serial data output signal of said first memory, said second differential serial data input signal, and said second differential serial data output signal each have a voltage within a range of about 200 millivolts to about 300 millivolts.
16. The memory system of claim 12 , wherein said first differential serial address input signal is buffered and provided as said first differential serial address output signal.
17. The memory system of claim 12 wherein the first data input/output port of the first transceiver is adapted to be configured as a multiplexed serial bus terminal by setting a control register bit.
18. The memory system of claim 12 wherein the first data input/output port of the first transceiver is configured to receive the first differential serial address input signal multiplexed with the first differential serial data input signal and the first input/output port of the first transceiver is configured to provide a first output address signal multiplexed with a second data output signal.
19. The memory system of claim 12 further comprising a third memory coupled to the second memory, wherein a column address strobe (CAS) latency is adjusted for the first, second, and third memories.
20. A method for accessing a memory formed on an integrated circuit, comprising:
providing a plurality of low voltage differential serial address input signals to an address terminal of a transceiver on the integrated circuit for accessing one or more memory cells;
determining if the memory is to be accessed for a read operation or a write operation; and
transmitting a plurality of low voltage differential serial data signals to a data terminal of the transceiver on the integrated circuit in response to the plurality of low voltage differential serial address input signals.
21. The method of claim 20 , wherein said plurality of low voltage differential serial address input signals are provided at a data rate of at least 2 gigabits per second.
22. The method of claim 20 , wherein the plurality of differential serial address input signals are provided as an address packet having a start bit, an end bit, and one or more control bits.
23. The method of claim 22 , further comprising storing the one or more control bits in a control register.
24. The method of claim 23 , wherein one of the one or more control bits is for determining if the memory is to be accessed for the read operation or the write operation.
25. The method of claim 20 , wherein the plurality of low voltage differential serial data signals are provided as data packets having a start bit and an end bit.
26. The method of claim 20 , further comprising chaining at least one additional memory to the memory for allowing the memory and the at least one additional memory to be accessed via only one two-wire address terminal and only one two-wire data terminal.
27. The method of claim 20 , further comprising chaining at least one additional memory to the memory for allowing the memory and the at least one additional memory to be accessed via a single two-wire terminal, wherein the plurality of differential serial address input signals and the plurality of differential serial data signals are multiplexed on a time slot basis via the single two-wire terminal.