Segmented memory having power-saving mode

摘要

A memory array is divided into multiple segments, each segment having one or more rows of bitcells. Each segment has control circuitry that controls whether the segment is in an active mode or a power-saving, sleep mode. The control circuitry ensures that a segment transitions from sleep mode to active mode before a row of the segment is accessed by driving a corresponding wordline high. The control circuitry also ensures that, at the end of a row access, the wordline is driven low before the corresponding segment is transitioned from active mode to sleep mode.

主权项

1. Apparatus having a memory array comprising a plurality of segments, a segment comprising:
one or more rows of memory cells, each row comprising two or more memory cells and a wordline interconnecting the memory cells of the row; and control circuitry configured to selectively enable and disable access to all of the segment and selectively enable and disable access to any individual row of the segment, wherein:
the control circuitry is configured to generate (i) a segment-enable control signal that controls access to all of the segment and (ii) a segment-level wordline-enable control signal that controls whether a wordline signal can be applied to the wordline of a row to be accessed, wherein (a) the wordline-enable control signal is distinct from the wordline signal and (b) the control circuitry is configured to gate the wordline-enable control signal with each wordline signal in a segment to control whether any wordline signal can be applied to a corresponding wordline of a row in the segment, such that:
when access to a row in the segment is to be initiated, the control circuitry generates the segment-enable control signal and the wordline-enable control signal to enables access to all of the segment before enabling access to the row and before the wordline signal can be applied to the wordline; andwhen access to the row in the segment is to be terminated, the control circuitry generates the segment-enable control signal and the wordline-enable control signal to disables access to the row and to disable the wordline signal from being applied to the wordline before disabling access to all of the segment.