Qualcomm Incorporated

Harish Shankar

Manish Garg

Rajesh Kumar

Joshua Lance Puckett

Rahul Krishnakumar Nadkarni

Michael ThaiThanh Phan

David Paul Hoff

Ramasamy Adaikkalavan

Michael Phan

Systems and methods for cache invalidation, with support for different modes of cache invalidation include receiving a matchline signal, wherein the matchline signal indicates whether there is a match between a search word and an entry of a tag array of the cache. The matchline signal is latched in a latch controlled by a function of a single bit mismatch clock, wherein a rising edge of the single bit mismatch clock is based on delay for determining a single bit mismatch between the search word and the entry of the tag array. An invalidate signal for invalidating a cacheline corresponding to the entry of the tag array is generated at an output of the latch. Circuit complexity is reduced by gating a search word with a search-invalidate signal, such that the gated search word corresponds to the search word for a search-invalidate and to zero for a Flash-invalidate.

Multi-mode cache invalidation

A memory system includes a sense amplifier electrically coupled to a first bitline and a second bitline associated with a column of a memory array, a bl transistor electrically coupled to the first bitline, wherein the bl transistor is configured to receive as input a first electrical signal from the first bitline, and a blb transistor electrically coupled to the second bitline, wherein the blb transistor is configured to receive as input a second electrical signal from the second bitline, wherein an output of the bl transistor and an output of the blb transistor are electrically coupled together as a common output, and wherein the sense amplifier is configured to receive as an input the common output of the bl transistor and the blb transistor.

Bitline-driven sense amplifier clocking scheme

Collision detection systems for detecting read-write collisions in memory systems after word line activation are disclosed. In one aspect, a collision detection system is provided. The collision detection system includes a collision detection circuit for each bit cell row of memory array. Each collision detection circuit is configured to receive a write and read word line signal corresponding to the bit cell row. The collision detection circuit is configured to detect a write and read word line signal pair being active for a write and read operation for the same bit cell row. The collision detection circuit is configured to generate a collision detection signal to notify clients associated with the memory system that a read-write collision occurred. Detecting the read-write collisions after read word line activation reduces or avoids overhead delays in the read path, as opposed to detecting read-write collisions prior to activation of the read word line.

Collision detection systems for detecting read-write collisions in memory systems after word line activation, and related systems and methods

Systems and methods for detecting and suppressing crowbar currents in memory arrays. A dummy read is implemented to prevent crowbar currents in the case of simultaneous read-write collisions in a static random access memory (SRAM) array having cross-coupled bitline keepers. When a simultaneous read and write operation to a first entry of the memory array is detected, the read operation to the first entry is suppressed and a dummy read operation to a second entry of the memory array is performed. The write operation to the first entry is allowed to proceed undisturbed.

Dummy read to prevent crowbar current during read-write collisions in memory arrays with crosscoupled keepers

In low power CPUs, the best way to reduce power is to reduce supply voltage. Most low voltage memory arrays use an 8T cell, which has read stability immunity, in order to operate at low voltages. An embodiment of the disclosure determines when a write wordline (WWL) rises. If the determination shows that the WWL has risen, at least one of the plurality of p-channel field effect transistors (pFETS) is disconnected from a voltage supply, and the at least one plurality of n-channel field effect transistors (nFET) passgate transistors are opened.

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Raleigh, NC, United States of America

Harish Shankar