RRAM Sense Circuit Using Bidirectional Current Mirrors
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Solution Overview
Problem
Existing sense circuits for RRAM devices face complexity and inefficiency in reading and writing operations due to the need to switch between sourcing and sinking memory current, requiring separate sub-circuits for forward and reverse read operations, which increases circuit complexity and area.
Innovation Solution
A sense circuit design that includes P-type and N-type current mirrors, switches, and a comparator, allowing the circuit to source or sink memory current in either direction, eliminating the need to switch between bit and source lines, thereby simplifying operations and reducing circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sense circuit switches between bit line and source line for forward and reverse read operations, then the read operations can be performed, but the circuit complexity increases
Solution Approach 1:
The sense circuit is designed to perform both forward and reverse read operations using the same circuit structure. The circuit can source current during forward reads and sink current during reverse reads without requiring separate sub-circuits, making the sense circuit universal and eliminating the need for line switching
Solution Approach 2:
The patent merges the functionality of separate sub-circuits into a single integrated sense circuit. By combining current mirroring mechanisms and control logic, the circuit achieves both sourcing and sinking capabilities in one structure, reducing overall device complexity
2Reliability
If separate sub-circuits are used for forward and reverse read operations, then each operation can be optimized, but the circuit area increases
Solution Approach 1:
A single sense circuit structure is designed to handle both forward and reverse read operations through current mirroring and control signals, eliminating the need for duplicate sub-circuits and reducing overall circuit area while maintaining operational optimization
Solution Approach 2:
The sense circuit uses dynamic control signals to switch between sourcing and sinking modes based on the required read operation. This dynamic operation allows the same physical circuit to adapt its behavior for different operations without requiring separate static circuits
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed sense circuit efficiently reads and writes RRAM cells by eliminating the need for separate sub-circuits, reducing circuit complexity and area, and allowing for more efficient read and write operations, while also omitting the source-line decoder.
Implementation Method 1
A sense circuit for a resistive random-access memory device includes a first current mirror, a second current mirror, a first switch, a second switch, and a comparator
Data Source
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AI summary
A resistive random-access memory device includes a RRAM array including a plurality of RRAM cells coupled to a source line, a controller, a bit-line decoder, and a sense circuit. Each of the RRAM cells storing a logic state and is selected by the corresponding bit line and word line. The controller selects a selected RRAM cell by a bit-line signal and a selected word line and determines the logic state according to a sense signal. The bit-line decoder couples a data bit line to the selected bit line according to a bit-line signal. The sense circuit is coupled to the data bit line and compares a memory current flowing through the selected RRAM with a reference current to generate the sense signal. The sense circuit sinks the memory current from the data bit line when operating in a reset operation and a reverse read operation. The sense circuit sources the memory current to the data bit line when operating in a set operation and a forward read operation.