Dynamic bit line voltage and sensing time enhanced read for data recovery
A method and system are provided for reading a non-transitory memory array. When a default read operation is performed and has failed, a dynamic sensing bit line voltage (VBLC) enhanced read or a dynamic sense time read is performed. According to the dynamic VBLC enhanced read or the dynamic sense time enhanced read, the VBLC or the sense time is increased, and a read is performed with the increased VBLC or increased sense time. If this enhanced read is unsuccessful, and if a maximum VBLC or a maximum sense time has not yet been reached, the VBLC or the sense time is increased again, and another read is performed. Once the maximum VBLC or a maximum sense time has been reached, if the read is still not successful, a read failure is reported.
1. A method of reading a non-transitory memory array, the method comprising:
performing a default read of a memory array by applying a default sensing bit line voltage (VBLC) and using a default sense time;
upon determining that the default read is unsuccessful, performing one of a dynamic VBLC enhanced read of the memory array and a dynamic sense time enhanced read of the memory array,
wherein the dynamic VBLC enhanced read comprises:
(a) increasing the VBLC, such that VBLC i =VBLC (i-1) +ΔVBLC, where i is a non-zero integer,
(b) performing a read of the memory array using the increased VBLC i ;
(c) if the read not successful, determining if the VBLC i has reached a voltage maximum;
(d) if the VBLC i has reached the voltage maximum, reporting a read failure;
(e) if the VBLC i has not reached the voltage maximum, repeating operations (a)-(e); and
wherein the dynamic sense time enhanced read comprises:
(a′) increasing the sense time t, such that t i =t (i-1) +Δt, where i is a non-zero integer,
(b′) performing a read of the memory array using the increased sense time t;
(c′) if the read not successful, determining if the sense time t i has reached a time maximum;
(d′) if the sense time t i has reached the time maximum, reporting a read failure;
(e′) if the sense time t i has not reached the voltage maximum, repeating operations (a′)-(e′).
2. The method according to claim 1 , wherein ΔVBLC is 50 mV and Δt is 200 ns.
3. The method according to claim 1 , wherein the voltage maximum is 300 mV, and the time maximum is 1200 ns.
4. A non-volatile memory storage system comprising:
a memory cell array comprising a plurality of blocks of memory cells; and
a dynamic enhanced read circuit configured to perform a default read of the memory cell array by applying a default sensing bit line voltage (VBLC) and using a default sense time, and upon determining that the default read is unsuccessful, perform one of a dynamic VBLC enhanced read of the memory cell array and a dynamic sense time enhanced read of the memory cell array,
wherein the dynamic VBLC enhanced read comprises:
(a) increasing the VBLC, such that VBLC i =VBLC (i-1) +ΔVBLC, where i is a non-zero integer,
(b) performing a read of the memory array using the increased VBLC i ;
(c) if the read not successful, determining if the VBLC i has reached a voltage maximum;
(d) if the VBLC i has reached the voltage maximum, reporting a read failure;
(e) if the VBLC i has not reached the voltage maximum, repeating operations (a)-(e); and
wherein the dynamic sense time enhanced read comprises:
(a′) increasing the sense time t, such that t i =t (i-1) +Δt, where i is a non-zero integer,
(b′) performing a read of the memory array using the increased sense time t;
(c′) if the read not successful, determining if the sense time t i has reached a time maximum;
(d′) if the sense time t i has reached the time maximum, reporting a read failure;
(e′) if the sense time t i has not reached the voltage maximum, repeating operations (a′)-(e′).
5. The system according to claim 4 , wherein ΔVBLC is 50 mV and Δt is 200 ns.
6. The system according to claim 4 , wherein the voltage maximum is 300 mV, and the time maximum is 1200 ns.
7. A non-volatile computer-readable medium having recorded thereon a program which, when executed by a processor, causes the processor to execute a method comprising:
performing a default read of a memory array by applying a default sensing bit line voltage (VBLC) and using a default sense time;
upon determining that the default read is unsuccessful, performing one of a dynamic VBLC enhanced read of the memory array and a dynamic sense time enhanced read of the memory array,
wherein the dynamic VBLC enhanced read comprises:
(a) increasing the VBLC, such that VBLC i =VBLC (i-1) +ΔVBLC, where i is a non-zero integer,
(b) performing a read of the memory array using the increased VBLC i ;
(c) if the read not successful, determining if the VBLC i has reached a voltage maximum;
(d) if the VBLC i has reached the voltage maximum, reporting a read failure;
(e) if the VBLC i has not reached the voltage maximum, repeating operations (a)-(e); and
wherein the dynamic sense time enhanced read comprises:
(a′) increasing the sense time t, such that t i =t (i-1) +Δt, where i is a non-zero integer,
(b′) performing a read of the memory array using the increased sense time t i ;
(c′) if the read not successful, determining if the sense time t i has reached a time maximum;
(d′) if the sense time t i has reached the time maximum, reporting a read failure;
(e′) if the sense time t i has not reached the voltage maximum, repeating operations (a′)-(e′).
8. The non-volatile computer-readable medium according to claim 7 , wherein ΔVBLC is 50 mV and Δt is 200 ns.
9. The non-volatile computer-readable medium according to claim 7 , wherein the voltage maximum is 300 mV, and the time maximum is 1200 ns.