Memory Cell Current Control via Clamp Transistor Regulation
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Solution Overview
Problem
Current non-volatile memory devices face challenges in achieving high capacity and performance while minimizing current and power consumption, particularly in massively parallel memory page operations.
Innovation Solution
The implementation of a non-volatile memory circuit with regulation circuitry, sense amps, and current control circuitry that compares and regulates the current supplied to bit lines with a reference level, using clamp transistors and a reference current source to optimize current determination and supply, enabling efficient programming and reading of memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If higher density and multi-state memory cells are used to increase storage capacity, then memory capacity increases, but current consumption and power requirements increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the reference current level based on the memory operation type (read, verify, or program). The system transitions between different current breakpoints (first breakpoint for read/verify, second breakpoint for program), allowing the memory device to optimize current consumption according to the specific operation being performed while maintaining accurate multi-state detection
Solution Approach 2:
The patent implements dynamics through the dynamic selection of reference current levels. The memory device can switch between different reference current breakpoints depending on whether a read, verify, or program operation is being performed. This dynamic adaptation allows the system to use lower current for read operations and higher current for program operations, resolving the contradiction between capacity and power consumption
2Quantity of substance
If more breakpoint levels are established to enable multi-state data storage, then data storage capacity increases, but device complexity and current control requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the current detection range into multiple discrete breakpoints. The first breakpoint level is used for read and verify operations, while the second breakpoint level is used for program operations. This segmentation allows the memory device to accurately detect multiple states without requiring a single complex continuous detection system
Solution Approach 2:
The patent uses an intermediary approach by introducing a programmable reference current source that can be set to different breakpoint levels. This intermediary reference current acts as a mediator between the memory cell states and the detection circuitry, simplifying the control logic by providing clear threshold levels for state determination
3Device complexity
If fixed reference current levels are used for all operations, then device simplicity is maintained, but reading accuracy and programming precision deteriorate
Solution Approach 1:
The patent implements dynamics by making the reference current level adaptive rather than fixed. The system automatically selects appropriate reference current breakpoints based on the operation type: using the first breakpoint for read/verify operations to achieve high measurement precision, and the second breakpoint for program operations. This dynamic adjustment maintains measurement accuracy without requiring permanently complex circuitry
Data Source
AI summary
Techniques and corresponding circuitry are presented for controlling the amount of current flowing through the cells of a memory circuit during a sensing operation though a feedback arrangement. The amount of current supplied to bit lines from an external power supply by regulation circuitry is compared with a reference level. Based on this comparison, the level on the control gates of clamp transistors in the sense amp circuits is set to control the amount of current supplied to the bit lines. This can reduce device variation since the levels are replicated locally at the generator on the chip. The circuitry can also be used more generally to determine the current level drawn during a sensing operation.