Circuit for preventing a dummy read in a memory
View Patent ↗A memory includes a row decoder, column logic, and a memory array having a plurality of memory cells arranged in rows and columns. A plurality of write word lines are coupled to the row decoder. A plurality of complementary write word lines is coupled to the row decoder. A plurality of read bit lines is coupled to the column logic. A plurality of write bit lines is coupled to the column logic. A plurality of column decoded write enable lines is coupled to the column logic. Each memory cell of the plurality of memory cells is coupled to a corresponding write control circuit. Each write control circuit comprises a transmission gate coupled between a column decoded write enable line and an access transistor of a memory cell. The transmission gate is controlled by a write word line signal.
1. A memory comprising:
a plurality of write word lines;
a plurality of complementary write word lines;
a plurality of write bit line pairs;
a plurality of read bit lines;
a plurality of read word lines;
a plurality of memory cells;
a plurality of column decoded write enable lines; and
a plurality of write control circuits, a write control circuit of the plurality of write control circuits comprising:
a transmission gate having a first current terminal coupled to a column decoded write enable line of the plurality of column decoded write enable lines, a second current terminal coupled to a control electrode of an access transistor of a memory cell of the plurality of memory cells, a first control terminal coupled to a write word line of the plurality of write word lines, and a second control terminal coupled to a complementary write word line of the plurality of complementary write word lines, wherein a signal on the column decoded write enable line is passed through to the control electrode of the access transistor when a signal on the write word line is asserted; and
a transistor having a first current electrode coupled to the second current terminal of the transmission gate, a second current electrode coupled to a power supply voltage terminal, and a control electrode coupled to the complementary write word line.
2. The memory of claim 1 , wherein the access transistor has a first current electrode coupled to a storage node of the memory cell, a second current electrode coupled to a write bit line of the plurality of write bit line pairs, and the control electrode coupled to the second current terminal of the transmission gate.
3. The memory of claim 1 , wherein the memory cell comprises:
a storage cell having a first storage node and a second storage node;
the access transistor having a first current electrode coupled to a first write bit line of the plurality of write bit lines, a second current electrode coupled to the first storage node, and the control electrode coupled to the second current terminal of the transmission gate; and
a read port for coupling data from the first storage node to a first read bit line of the plurality of read bit lines.
4. The memory of claim 1 , wherein the transmission gate comprises:
a first transistor having a first current electrode coupled to the column decoded write enable line, a second current electrode coupled to the access transistor of the memory cell, and a control electrode coupled to the write word line; and
a second transistor having a first current electrode coupled to the first current electrode of the first transistor, a second current electrode coupled to the second current electrode of the first transistor, and a control electrode coupled to the complementary write word line.
5. A memory comprising:
a row decoder;
a column logic; and
a memory array coupled to the row decoder and the column logic, comprising:
a plurality of memory cells arranged in rows and columns;
a plurality of write word lines coupled to the row decoder, running in a row direction;
a plurality of complementary write word lines coupled to the row decoder, running in a row direction;
a plurality of read bit lines, coupled to the column logic, running in a column direction that carry data that has been read from the plurality of memory cells;
a plurality of write bit lines, coupled to the column logic, running in the column direction, wherein the write bit lines carry data for writing into the plurality of memory cells;
a plurality of decoded write enable lines, coupled to the column logic, running in the column direction;
a plurality of write control circuits;
wherein:
each memory cell of the plurality of memory cells is coupled to a predetermined one of the plurality of write control circuits, a predetermined one of the read bit lines of the plurality of read bit lines, and a first predetermined one of the write bit lines of the plurality of write bit lines;
each write control circuit comprises:
a transmission gate having a first control input coupled to one of the plurality of write word lines, a second control input coupled to one of the plurality of complementary write word lines, an input coupled to one of the plurality of decoded write enable lines, and an output coupled to one of the plurality of memory cells, wherein a signal on the one of the plurality of decoded write enable lines is passed through to the one of the plurality of memory cells when a signal on the write word line is asserted; and
a first transistor having a control electrode coupled to the complementary write word line input, a first current electrode coupled to a ground terminal, and a second current electrode coupled to the output of the transmission gate.
6. The memory of claim 5 , wherein the transmission gate further comprises:
a second transistor having a first current electrode coupled to the one of the plurality of decoded write enable lines, a second current electrode coupled to the second current electrode of the first transistor, and a control input coupled to the complementary write word line input.
7. The memory of claim 6 , wherein the transmission gate further comprises:
a third transistor having a first current electrode coupled to the first current electrode of the second transistor, a second current electrode coupled to the second current electrode of the second transistor, and a control electrode coupled to the write word line input.
8. The memory of claim 5 , wherein the plurality of decoded write enable lines provide a plurality of write enable signals for controlling write operations in the plurality of memory cells in response to a column address signal.
9. The memory of claim 5 , wherein the transmission gate passes a logic high signal when a write enable signal provided by the one of the plurality of write enable lines is a logic high and the transmission gate passes a logic low signal when the write enable signal is a logic low.
10. The memory of claim 5 , wherein the first transistor is an N-channel transistor.
11. The memory of claim 7 , wherein the second transistor is a P-channel transistor and the third transistor is an N-channel transistor.
12. The memory of claim 5 , wherein each memory cell has a first storage node and a second storage node.
13. The memory of claim 12 , wherein each memory cell has a second transistor having a first current electrode coupled to the first predetermined one of the plurality of write bit lines, a second current electrode coupled to the first storage node, and a control electrode coupled to the write control circuit.
14. The memory of claim 12 , wherein each memory cell has a read port coupled to a predetermined one of the first storage node and the second storage node and coupled to the predetermined one of the read bit lines.
15. The memory of claim 13 , wherein each memory cell has a third transistor having a first current electrode coupled to a predetermined one of the complementary write bit lines, a second current electrode coupled to the second storage node, and a control electrode coupled to the write control circuit.
16. The memory of claim 5 wherein the plurality of memory cells is powered by a power supply voltage not greater than about one volt.
17. A memory comprising:
a plurality of write word lines oriented substantially in a first direction;
a plurality of complementary write word lines oriented substantially in the first direction;
a plurality of write bit lines oriented substantially in a second direction;
a plurality of complementary write bit lines oriented substantially in the second direction;
a plurality of read bit lines oriented substantially in the second direction;
a plurality of read word lines oriented substantially in the first direction;
a plurality of memory cells;
a plurality of write enable lines oriented substantially in the second direction; and
a plurality of write control circuits, a write control circuit of the plurality of write control circuit corresponds to a memory cell of the plurality of memory cells, each of the plurality of write control circuits comprising:
a first transistor having a first current electrode coupled to a write enable line of the plurality of write enable lines, a second current electrode coupled to the memory cell, and a control electrode coupled to a write word line of the plurality of write word lines;
a second transistor having a first current electrode coupled to the first current electrode of the first transistor, a second current electrode coupled to the second current electrode of the first transistor, and a control electrode coupled to a complementary write word line of the plurality of complementary write word lines; and
a third transistor having a first current electrode coupled to the memory cell, a second current electrode coupled to a power supply voltage terminal, and a control electrode coupled to the complementary write word line, and wherein a signal on the write enable line is passed through to the memory cell when a signal on the write word line is asserted.
18. The memory of claim 17 , wherein the memory cell comprises:
a storage cell having a first storage node and a second storage node;
a first access transistor having a first current electrode coupled to the first storage node, a second current electrode coupled to a write bit line of the plurality of write bit lines, and a control electrode coupled to the second current electrodes of the first and second transistors; and
a second access transistor having a first current electrode coupled to the second storage node, a second current electrode coupled to a complementary write bit line of the plurality of complementary write bit lines, and a control electrode coupled to the second current electrodes of the first and second transistors.
19. The memory of claim 18 , wherein the plurality of write enable lines is coupled to a column decoder.
20. The memory of claim 17 , wherein the first and third transistors are characterized as being N-channel transistors and the second transistor is characterized as being a P-channel transistor.