Non-Differential NVM Readout Circuit Low Power Design
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Solution Overview
Problem
Conventional readout circuits for non-volatile memory (NVM) devices require large steady currents for reading stored information, leading to high power consumption and circuit complexity due to the need for reference currents and voltage.
Innovation Solution
The proposed readout circuitry eliminates the requirement for large steady currents by using a non-differential type design that avoids device mismatch offsets and operates without a reference current or voltage, employing a P-type MOSFET and NMOS transistors to manage bit line voltages and discharge during read and standby modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional readout circuit with reference current is used to read NVM data, then the stored information can be detected and determined, but large steady currents are required leading to high power consumption
Solution Approach 1:
The patent extracts and removes the reference current generation circuitry from the readout system. By eliminating the reference current source, the circuit no longer requires large steady currents to be supplied continuously, thereby reducing power consumption while maintaining the ability to detect stored information through alternative sensing mechanisms
Solution Approach 2:
The patent employs periodic pulsing of the bit line instead of continuous steady current. The bit line is pulsed to a first voltage level to enable reading during active periods, then returned to a second voltage level during standby periods. This periodic action allows information detection when needed while minimizing power consumption during non-reading operations
2Measurement precision
If reference current generation circuitry is included in the readout circuit, then current comparison can be performed, but circuit complexity increases
Solution Approach 1:
The patent removes the reference current generation circuitry from the readout system. By extracting this complex subsystem, the overall circuit complexity is reduced while the essential function of detecting stored information is maintained through simplified voltage sensing on the bit line without requiring current comparison against a reference
3Measurement precision
If a differential amplifier comparator is used to compare currents, then NVM conductance can be determined, but offset caused by device mismatch occurs
Solution Approach 1:
The patent removes the differential amplifier comparator from the readout circuit. By eliminating this component, the source of offset errors due to device mismatch is removed. The circuit instead determines NVM conductance through direct voltage sensing on the bit line, avoiding the comparative measurement process that introduces mismatch-related offsets
Solution Approach 2:
The patent uses a simplified sensing approach that copies the bit line voltage directly for measurement without requiring complex differential comparison. This direct copying method avoids the introduction of offset errors that would otherwise be generated by mismatched differential amplifier components
Data Source
AI summary
Non-differential sense amplifier circuitry for reading out Non-Volatile Memories (NVMs) and its operating methods are disclosed. Such non-differential amplifier circuitry requires exceptionally low power and achieves moderate sensing speed, as compared to a conventional sensing scheme.