Memory device with improved driver operation and methods to operate the memory device

1 . A memory device comprising:

memory cells at cross points of access lines of a memory array; and

a two-transistor driver comprising a P-type transistor and a N-type transistor connected to the P-type transistor, the two-transistor driver being configured to:

drive a first one of the access lines to a first read/program voltage comprising a positive voltage via a source line of the P-type transistor of the two-transistor driver, during a PULSE phase, when the first one of the access lines is an addressed access line and while a source line of the N-type transistor is at a floating voltage and a gate line of the P-type transistor and a gate line of the N-type transistor are at a discharging voltage;

drive the first one of the access lines to a second read/program voltage comprising a negative voltage via the source line of the N-type transistor of the two-transistor driver, during the PULSE phase, when the first one of the access lines is the addressed access line and while the source line of the P-type transistor is at the floating voltage and the gate line of the P-type transistor and the gate line of the N-type transistor are at the discharging voltage; and

drive the first one of the access lines physically adjacent to a second one of the access lines to a shielding voltage through the two-transistor driver, during the PULSE phase, when the first one of the access lines is an unaddressed access line and the second one of the access lines is the addressed access line.

2 . The memory device of claim 1 , comprising a second two-transistor driver comprising the P-type transistor and the N-type transistor connected to the P-type transistor, the second two-transistor driver being configured to:

drive the second one of the access lines to the first read/program voltage or the second read/program voltage through the second two-transistor driver, during the PULSE phase, when the second one of the access lines is the addressed access line; and

drive the second one of the access lines to the shielding voltage through the second two-transistor driver, during the PULSE phase, when the second one of the access lines is the unaddressed access line and the first one of the access lines is the addressed access line.

3 . The memory device of claim 1 , the two-transistor driver being configured to:

drive the first one of the access lines to the discharging voltage during an IDLE phase; and

drive the first one of the access lines to the floating voltage during an ACTIVE phase.

4 . The memory device of claim 3 , wherein the two-transistor driver is configured so that:

in the IDLE phase, gates of the P-type transistor and of the N-type transistor are at a respective inhibit gate voltage for the P-type transistor and pass gate voltage for the N-type transistor, in the ACTIVE phase the gate of the P-type transistor is at an inhibit gate voltage and the gate of the N-type transistor is at the inhibit gate voltage, and in the PULSE phase the gates of the P-type transistor and of the N-type transistor are at the discharging voltage;

in the IDLE phase, a source node of the N-type transistor is at the discharging voltage, in the ACTIVE phase the source node of the N-type transistor is at the floating voltage, and in the PULSE phase the source node of the N-type transistor is at the second read/program voltage or at the floating voltage based on an access operation to a cell coupled to the access line; and

in the ACTIVE phase, a source node of the P-type transistor is at the floating voltage, and in the PULSE phase the source node of the P-type transistor is at the first read/program voltage or at the floating voltage based on the access operation to the cell coupled to the access line.

5 . The memory device of claim 1 , comprising:

a first even two-transistor driver configured to drive a first even access line to the first read/program voltage or the second read/program voltage during the PULSE phase; and

a first odd two-transistor driver configured to drive a first odd access line to the shielding voltage during the PULSE phase,

wherein the first odd access line is physically adjacent to the first even access line.

6 . The memory device of claim 5 , wherein:

the first even two-transistor driver comprises a first even P-type transistor and a first even N-type transistor with gates coupled to respective even group gate driving lines, and sources coupled to respective first even source driving lines, and

the first odd two-transistor driver comprises a first odd P-type transistor and a first odd N-type transistor with gates coupled to respective odd group gate driving lines, and sources coupled to respective first odd source driving lines,

the memory device further comprising:

a second even two-transistor driver comprising a second even P-type transistor and a second even N-type transistor with gates coupled to the respective even group gate driving lines, and sources coupled to respective second even source driving lines, the second even two-transistor driver being configured to drive a second even access line to the shielding voltage during the PULSE phase; and

a second odd two-transistor driver comprising a second odd P-type transistor and a second odd N-type transistor with gates coupled to the respective odd group gate driving lines, and sources coupled to respective second odd source driving lines, the second odd two-transistor driver being configured to drive a second odd access line to the shielding voltage during the PULSE phase,

wherein the second odd access line is physically adjacent to the first even access line.

7 . The memory device of claim 5 , wherein:

the first even two-transistor driver comprises a first even P-type transistor and a first even N-type transistor with gates coupled to respective even group gate driving lines, and sources coupled to respective first even source driving lines,

the first odd two-transistor driver comprises a first odd P-type transistor and a first odd N-type transistor with gates coupled to respective odd group gate driving lines, and sources coupled to respective first odd source driving lines,

the memory device further comprising:

a second even two-transistor driver comprising a second even P-type transistor and a second even N-type transistor with gates coupled to the respective even group gate driving lines, and sources coupled to respective second even source driving lines, the second even two-transistor driver being configured to drive a second even access line to the shielding voltage during the PULSE phase; and

a second odd two-transistor driver comprising a second odd P-type transistor and a second odd N-type transistor with gates coupled to respective second odd group gate driving lines different from the respective odd group gate driving lines, and sources coupled to respective second odd source driving lines, the second odd two-transistor driver being configured to drive a second odd access line to the shielding voltage during the PULSE phase,

wherein the second odd access line physically adjacent to the first even access line.

8 . The memory device of claim 5 , comprising:

a plurality of even two-transistor drivers organized in even groups, each driver being coupled to a respective even access line, the first even two-transistor driver being in a first group of the plurality of even two-transistor drivers; and

a plurality of odd two-transistor drivers organized in odd groups, each driver being coupled to a respective odd access line, the first odd two-transistor driver being in a first group of the plurality of odd two-transistor drivers,

wherein respective even access lines and respective odd access lines alternate in a deck of the memory device.

9 . The memory device of claim 8 , wherein:

the first even access line is physically adjacent to a respective odd access line coupled to a second odd two-transistor driver in the first group of the plurality of odd two-transistor drivers, or

the first even access line is physically adjacent to a respective odd access line coupled to a second odd two-transistor driver in a second group of the plurality of odd two-transistor drivers.

10 . The memory device of claim 8 , comprising a controller configured to switch from an ACTIVE phase to the PULSE phase by selecting a specific group of a plurality of groups, wherein selecting the specific group comprises driving gates of the specific group to the discharging voltage, remaining groups of the plurality of groups being in the ACTIVE phase.

11 . The memory device of claim 1 , wherein the discharging voltage and the shielding voltage are a ground voltage, and wherein the first read/program voltage is the positive voltage and the second read/program voltage is the negative voltage having a same magnitude as the first read/program voltage.

12 . A method to operate a memory device, the method comprising:

during a PULSE phase;

driving an access line coupled a memory cell to a first read/program voltage comprising a positive voltage through a P-type transistor of a two-transistor driver by:

applying the first read/program voltage via a source line of the P-type transistor while a source line of an N-type transistor of the two-transistor driver is at a floating voltage, wherein the P-type transistor is connected to the N-type transistor; and

applying a discharging voltage to a gate line of the P-type transistor and a gate line of the N-type transistor.

13 . The method of claim 12 , further comprising:

during an IDLE phase, driving the access line coupled to the discharging voltage through the two-transistor driver; and

during an ACTIVE phase, driving the access line to the floating voltage through the two-transistor driver.

14 . The method of claim 13 , comprising:

during the IDLE phase:

driving an even access line coupled to the memory cell to the discharging voltage through an even two-transistor driver, and

driving an odd access line adjacent to the even access line to the discharging voltage through an odd two-transistor driver;

during the ACTIVE phase:

driving the even access line to the floating voltage through the even two-transistor driver, and

driving the odd access line adjacent to the even access line to the floating voltage through the odd two-transistor driver; and

during the PULSE phase:

driving the even access line to the first read/program voltage through the even two-transistor driver, and

driving the odd access line adjacent to the even access line to a shielding voltage through the odd two-transistor driver.

15 . The method of claim 14 , further comprising, during the PULSE phase of the even access line, driving another access line adjacent to the even access line to the shielding voltage through a respective two-transistor driver coupled to the another access line.

16 . The method of claim 14 , further comprising:

receiving a read or a write command to the memory cell in a memory portion;

if in the IDLE phase, transitioning the memory portion from the IDLE phase to the ACTIVE phase based on receiving the read or the write command, and then transitioning from the ACTIVE phase to the PULSE phase;

if in the ACTIVE phase, transitioning the memory portion from the ACTIVE phase to the PULSE phase based on receiving the read or the write command;

executing the PULSE phase in the memory portion, increasing a read/program counter and returning the memory portion to the ACTIVE phase based on the executing; and

maintaining the memory portion in the ACTIVE phase based on the read/program counter and/or a time counter not meeting a respective threshold, or

returning the memory portion to the IDLE phase based on the read/program counter or the time counter meeting the respective threshold.

17 . The method of claim 16 , wherein returning the memory portion to the ACTIVE phase based on the executing comprises driving the even access line to the discharge voltage after driving the even access line to the first read/program voltage or a second read/program voltage.

18 . The method of claim 16 , wherein transitioning the memory portion from the IDLE phase to the ACTIVE phase further comprises resetting the read/program counter and/or the time counter.

19 . The method of claim 12 , comprising:

during the PULSE phase:

driving the access line to a second read/program voltage comprising a negative voltage through the N-type transistor by:

applying the second read/program voltage via the source line of the N-type transistor while the source line of the P-type transistor is at the floating voltage; and

applying the discharging voltage to the gate line of the P-type transistor and the gate line of the N-type transistor.

20 . A system comprising a memory array and a controller configured to:

drive a first access line to a read/program voltage through a first two-transistor driver by applying a positive read/program voltage to a source line of a P-type transistor of the first two-transistor driver or a negative read/program voltage to a source line of an N-type transistor of the first two-transistor driver, and applying a discharging voltage to a gate line of the P-type transistor and a gate line of the N-type transistor, during a PULSE phase; and

drive a second access line physically adjacent to the first access line to a shielding voltage through a second two-transistor driver, during the PULSE phase.