Patent ID: 8923062

Claim:
A system for determining a read threshold, comprising: a read threshold generator configured to: determine a first number of solid state storage cells having a stored voltage which falls into a first voltage range, where the first voltage range is [R2, R1], including by: obtaining Z R1 , which is the number of solid state storage cells read back as a 0 when read at a read threshold of R1; and obtaining Z R2 , which is the number of solid state storage cells read back as a 0 when read at a read threshold of R2; determine a second number of solid state storage cells having a stored voltage which falls into a second voltage range, where the second voltage range is [R3, R2] and (R1−R2)=(R2−R3), including by: obtaining Z R3 , which is the number of solid state storage cells read back as a 0 when read at a read threshold of R3; determine a gradient by taking a difference between the first number of solid state storage cells and the second number of solid state storage cells; and determine a next read threshold based at least in part on the gradient; and an interface configured to communicate with solid state storage.