Write driver scheme for bit-writable memories
The apparatus provided may be a memory circuit. The memory circuit includes a memory cell. The memory cell has a bitline. The memory circuit also includes a write driver. The write driver is configured to drive the bitline to write a bit to the memory cell during a write operation. The write driver is also configured to float the bitline to mask the bit during a read operation. The write driver may use NMOS pullup transistors.
1. A memory circuit, comprising:
a memory cell having a bitline;
a write driver having a pullup circuit configured to drive the bitline to write a bit to the memory cell during a write operation and to float the bitline to mask the bit during a read operation; and
a write multiplexer circuit configured to switchably couple the pullup circuit to the bitline.
2. The memory circuit of claim 1 , wherein the pullup circuit includes a pair of n-channel metal-oxide-semiconductor field effect (NMOS) transistors.
3. The memory circuit of claim 1 , wherein the write multiplexer circuit comprises NMOS transistors.
4. The memory circuit of claim 1 , further comprising a pulldown circuit coupled to the pullup circuit and the multiplexer output, the pulldown circuit controlled by the control input.
5. The memory circuit of claim 4 , wherein the pulldown circuit comprises a pair of NMOS transistors.
6. A processing system comprising:
a processor;
a memory circuit coupled to the processor, the memory circuit including:
a memory cell having a bitline,
a write driver having a pullup circuit configured to drive the bitline to write a bit to the memory cell during a write operation and to float the bitline to mask the bit during a read operation; and
a write multiplexer circuit configured to switchably couple the pullup circuit to the bitline.
7. The memory circuit of claim 6 , wherein the pullup circuit includes a pair of n-channel metal-oxide-semiconductor field effect (NMOS) transistors.
8. The memory circuit of claim 6 , wherein the write multiplexer circuit comprises NMOS transistors.
9. The memory circuit of claim 6 , further comprising a pulldown circuit coupled to the pullup circuit and the multiplexer output, the pulldown circuit controlled by the control input.
10. The memory circuit of claim 9 , wherein the pulldown circuit comprises a pair of NMOS transistors.
11. A memory circuit, comprising:
means for storing a bit, the means for storing a bit having a bitline;
means for driving the bitline to write the bit to the means for storing the bit during a write operation and to float the bitline to mask the bit during a read operation, the means for driving the bitline having a pullup circuit; and
means for switchably coupling the pullup circuit to the bitline.
12. The memory circuit of claim 11 , wherein the pullup circuit includes a pair of n-channel metal-oxide-semiconductor field effect (NMOS) transistors.
13. The memory circuit of claim 11 , wherein the means for multiplexing comprises NMOS transistors.
14. The memory circuit of claim 11 , further comprising a pulldown circuit coupled to the pullup circuit and the output of the means to multiplex, the pulldown circuit controlled by the control input.
15. The memory circuit of claim 14 , wherein the pulldown circuit comprises a pair of NMOS transistors.