TRACKING MECHANISM FOR WRITING TO A MEMORY CELL

• US 20140032871A1
• Filed: 07/27/2012
• Published: 01/30/2014
• Est. Priority Date: 07/27/2012
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Hsu, Kuoyuan (Peter), Wang, Bing, Tao, Derek C., Tang, Yukit, Fan, Kai
• Granted Patent: US 8,964,492 B2
• Time in Patent Office: Days
• US Class Current: 711/167
• CPC Class Codes: G11C 11/419 Read-write [R-W] circuits
• CPC Class Codes: G11C 7/12 Bit line control circuits, e.g. drivers, boosters, pull-up circuits, pull-down circuits, precharging circuits, equalising circuits, for bit lines
• CPC Class Codes: G11C 7/222 Clock generating, synchronizing or distributing circuits within memory device
• CPC Class Codes: G11C 7/227 Timing of memory operations based on dummy memory elements or replica circuits

Abstract

A circuit includes a tracking write circuit and a write circuit. Various write signals of the write circuit are generated based on tracking signals of the tracking write circuit. The write signals are used in a write operation of a memory cell.

Claims

1. A circuit comprising:

a clock signal line configured to have a clock signal thereon;

a write driver;

a data circuit;

a memory cell;

a tracking write buffer;

a tracking write driver; and

a tracking cell,

wherein the circuit is configured so that during a write operation of the memory cell based on the clock signal

the write driver circuit is configured to generate a write control signal on a write control line to control the memory cell;

the data circuit is configured to provide write data to the memory cell on a write data line;

the tracking write buffer is configured to generate a tracking write control signal on a tracking write control line to control the tracking cell;

the tracking write driver is configured to generate a tracking write data signal on a tracking write data line to be transferred to the tracking cell;

the data to be transferred to the tracking cell is transferred to the tracking cell based on a slower signal of the tracking write control signal and the tracking write data signal; and

the tracking cell is configured to generate a tracking signal based on the data transferred to the tracking cell.

2. The circuit of claim 1, wherein the circuit is part of a memory macro.

3. The circuit of claim 2, wherein the memory macro is configured to receive the clock signal from outside of the memory macro.

4. The circuit of claim 1, wherein

the write control line is coupled with a first plurality of memory cells;

the write data line is coupled with a second plurality of memory cells;

the tracking write control line is coupled with a third plurality of memory cells;

the tracking write data line is coupled with a fourth plurality of memory cells;

the first plurality of memory cells is substantially equal to the third plurality of memory cells; and

the second plurality of memory cells is substantially equal to the fourth plurality of memory cells.

5. The circuit of claim 1, wherein

the memory cell includes a cell node configured to receive a cell P-side current, a cell N-side current, and a cell pass gate current;

values of the cell P-side current, the cell N-side current, and the cell pass gate current are related to one another by a first ratio;

the tracking cell includes a tracking node configured to receive a tracking cell P-side current, a tracking cell N-side current, and a tracking cell pass gate current;

values of the tracking cell P-side current, the tracking cell N-side current, and the tracking cell pass gate current are related to one another by a second ratio; and

the first ratio is substantially equal to the second ratio.

6. The circuit of claim 1, wherein

the circuit is configured to meet at least one of the following conditions:

the tracking write control line is configured to have a tracking control resistance being at least equal to a resistance of the write control line;

the tracking write control line is configured to have a tracking control capacitance being at least equal to a capacitance of the write control line;

the tracking write data line is configured to have a tracking data resistance being at least equal to a resistance of the write data line;

or

the tracking write data line is configured to have a tracking data capacitance being at least equal to a capacitance of the write data line.

7. The circuit of claim 1, wherein

the circuit is configured to meet at least one of the following conditions:

the tracking write control line is configured to have a tracking control time delay being at least equal to a time delay of the write control line;

or

the tracking write data line is configured to have a tracking data time delay being at least equal to a time delay of the write data line.

8. The circuit of claim 1, wherein

transistors in the memory cell are of a first type manufactured by a memory process;

and

transistors in the tracking cell are of a second type manufactured by a logic process.

9. A method of writing to a memory cell comprising:

based on a clock signal,

generating a first edge of a write control signal on a write control line of the memory cell;

generating a first edge of a write data signal on a write data line of the memory cell;

generating a first edge of a tracking write control signal on a tracking write control line; and

generating a first edge of a tracking write data signal on a tracking write data line;

based on a slower signal of the tracking write control signal and the tracking write data signal,

generating a reset signal; and

based on the reset signal,

generating a second edge of the write control signal; and

generating a second edge of the write data signal,

wherein

a time delay of the tracking write control signal is greater than a time delay of the write control signal; and

a time delay of the tracking write data signal is greater than a time delay of the write data signal.

10. The method of claim 9, further comprising:

based on the reset signal,

generating a second edge of the tracking write control signal; and

generating a second edge of the tracking write data signal.

11. The method of claim 9, further comprising

receiving the clock signal from outside of a memory macro having the memory cell.

12. The method of claim 9, wherein

the write control line is a write word line of a memory macro;

the write data line is a write bit line of the memory macro;

the tracking write control line is coupled with a first plurality of memory cells; and

the tracking write data line is coupled with a second plurality of memory cells.

13. The method of claim 9, further comprising

based on the slower signal of the tracking write control signal and the tracking write data signal and before generating the reset signal,

transferring data represented by the tracking write data signal to a node of a tracking cell coupled with the tracking write control line and with the tracking write data line;

and

generating an output signal of the tracking cell.

14. A tracking circuit in a memory macro comprising:

a clock generator circuit;

a tracking cell;

a tracking write buffer;

a first plurality of memory cells;

a tracking write control line coupled with the tracking cell, the tracking write buffer, and the first plurality of memory cells;

a tracking write driver;

a second plurality of memory cells; and

a tracking write data line coupled with the tracking cell, the tracking write driver, and the second plurality of memory cells,

wherein

the clock generator circuit is configured to receive a first clock signal from outside of the memory macro, and, based on the first clock signal, generate a first edge of a second clock signal;

the tracking write buffer, based on the first edge of the second clock signal, is configured to generate a first edge of a tracking write control signal on the tracking write control line;

the tracking write driver, based on the first edge of the second clock signal, is configured to generate a first edge of a tracking write data signal on the tracking write data line; and

the tracking cell is configured to be written with data represented by the tracking write data signal based on a slower signal of the tracking write control signal and the tracking write data signal.

15. The tracking circuit of claim 14, wherein

the tracking cell includes a tracking node having a tracking P-side current, a tracking N-side current, and a tracking pass gate current;

a value of the tracking P-side current and a value of the tracking N-side current have a first relationship;

the value of the tracking P-side current and a value of the tracking pass gate current have a second relationship;

the value of the tracking N-side current and the value of the tracking pass gate current have a third relationship;

a memory cell of the memory macro includes a cell node having a cell P-side current, a cell N-side current, and a cell pass gate current;

a value of the cell P-side current and a value of the cell N-side current have a fourth relationship;

the value of the cell P-side current and a value of the cell pass gate current have a fifth relationship;

the value of the cell N-side current and the value of the cell pass gate current have a sixth relationship;

the first relationship and the fourth relationship are substantially the same;

the second relationship and the fifth relationship are substantially the same; and

the third relationship and the sixth relationship are substantially the same.

16. The tracking circuit of claim 14, wherein

an effective time delay of the tracking write control line is equal to or greater than an effective time delay of a write control line of the memory macro;

the write control line is associated with a memory cell of the memory macro to be written;

an effective time delay of the tracking write data line is equal to or greater than an effective time delay of a write data line of the memory macro; and

the write data line is associated with the memory cell of the memory macro to be written.

17. The tracking circuit of claim 14, wherein

a memory cell of the memory macro has a first plurality of transistors;

the tracking cell has a second plurality of transistors; and

a configuration of the first plurality of transistor is substantially similar to a configuration of the second plurality of transistors.

18. The tracking circuit of claim 14, wherein

a number of memory cells of the first plurality of memory cells is the same as a number of memory cells of a third plurality of memory cells;

the third plurality of memory cells is coupled with a write control line of the memory macro;

the write control line is associated with a memory cell of the memory macro to be written;

a number of memory cells of the second plurality of memory cells is the same as a number of memory cells of a fourth plurality of memory cells;

the fourth plurality of memory cells is coupled with a write data line of the memory macro; and

the write data line is associated with the memory cell of the memory macro to be written.

19. The tracking circuit of claim 14, wherein

the tracking cell is configured to generate an output signal upon being written with the data represented by the tracking write data signal;

the clock generator is configured to generate a second edge of the second clock signal based on the output signal of the tracking cell;

the tracking write buffer, based on the second edge of the second clock signal, is configured to generate a second edge of the tracking write control signal on the tracking write control line; and

the tracking write driver, based on the second edge of the second clock signal, is configured to generate a second edge of the tracking write data signal on the tracking write data line.

20. The tracking circuit of claim 14, wherein

transistors in the tracking cell are of a first type manufactured by a logic process;

and

transistors in memory cells of the memory macro are of a second type manufactured by a memory process.