Memory Assembly Body Biasing for Unstable Bit Filtering
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Solution Overview
Problem
Conventional memory assemblies suffer from unstable bits that interfere with device functionality and reliability, particularly in critical applications like physically unclonable functions (PUF), where these bits are not used for key generation and are disregarded in memory storage and retrieval.
Innovation Solution
A memory assembly structure with a pair of memory transistors and diode-connected transistors, coupled through a multiplexer, and a bias voltage source that applies different bias voltages to adjust the threshold voltage margin of the transistors to filter out unstable bits during reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional memory assemblies are used without body biasing, then the device structure is simpler, but unstable bits interfere with device functionality and reliability
Solution Approach 1:
The patent applies body biasing voltage to dynamically adjust the threshold voltage of transistors in memory cells and sense amplifiers. By changing the electrical parameter (threshold voltage) through biasing, the system filters out unstable bits during reading operations, thereby improving reliability without requiring fundamental structural changes to the memory architecture
Solution Approach 2:
The patent introduces body biasing circuits as an intermediary component between the power supply and the transistor bodies. These biasing circuits act as mediators that selectively adjust transistor threshold voltages to prevent unstable bits from being read, resolving the reliability issue without directly modifying the core memory cell structure
2Reliability
If body biasing is applied to filter unstable bits, then stable memory cells become more readable, but additional bias voltage sources and circuitry are required
Solution Approach 1:
The body biasing circuits are designed to serve multiple functions: they adjust threshold voltages in memory cells, control sense amplifier operation, and filter unstable bits during reading. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby limiting the increase in device complexity while achieving reliable unstable bit filtering
3Reliability
If body biasing is used to adjust threshold voltage margin, then reading stability improves, but power consumption increases
Solution Approach 1:
The body biasing is applied selectively during reading operations rather than continuously. The bias voltage sources activate only when memory cells are being accessed, adjusting threshold voltages temporarily to ensure stable reading. After the read operation completes, the biasing is removed or reduced, thereby maintaining reading stability while minimizing continuous power consumption
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
Improves the readability of stable memory cells by preventing unstable data bits from being read, enhancing the reliability and functionality of memory assemblies, especially in PUF applications, while minimizing chip surface area and power consumption.
Implementation Method 1
a bias voltage source coupled to each body of the pair of diode-connected transistors, wherein the bias voltage source applies a different bias voltage to each body of the pair of diode-connected transistors
Data Source
AI summary
Embodiments of the disclosure provide a memory assembly with body biasing and related methods to operate such a structure. A structure according to the disclosure includes a memory cell having a pair of memory transistors each having a gate coupled to a word line. A pair of diode-connected transistors each have a source/drain (S/D) terminal coupled to a respective S/D terminal of one of the pair of memory transistors through a multiplexer. A bias voltage source is coupled to each body of the pair of diode-connected transistors or each body of the pair of memory transistors. The bias voltage source applies a different bias voltage to each body of the pair of diode-connected transistors or each body of the pair of memory transistors.