Current Injection Sensing Amplifier for Low Voltage Memory
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Solution Overview
Problem
Existing non-volatile memory cell sensing circuits face challenges in operating at lower voltage supply levels and consuming less power due to the limitations of current mirrors using PMOS transistors, which cause a voltage threshold drop.
Innovation Solution
A sensing circuit utilizing a current injector with four output lines, where three lines connect to reference cells and one to the selected memory cell, providing a consistent current source for comparison, allowing for accurate determination of the memory cell's state without relying on current mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current mirrors utilizing PMOS transistors are used for sensing, then current comparison functionality is achieved, but voltage threshold drop occurs and operating voltage must be higher
Solution Approach 1:
The patent extracts the PMOS transistor from the sensing circuit, specifically removing the current mirror structure that relies on PMOS devices. By taking out the problematic component (PMOS transistor), the voltage threshold drop is eliminated, allowing the sensing amplifier to operate at lower voltages while maintaining current comparison functionality through alternative circuit design
Solution Approach 2:
The patent substitutes the PMOS-based current mirror mechanism with an NMOS-based sensing amplifier design. This replacement eliminates the inherent voltage threshold limitations of PMOS transistors and allows operation at reduced voltage levels, achieving the same current comparison function through a different physical implementation
2Reliability
If current mirrors utilizing PMOS transistors are used for sensing, then current comparison functionality is achieved, but power consumption increases
Solution Approach 1:
The patent removes the PMOS current mirror structure from the sensing circuit, eliminating the source of excessive power consumption associated with PMOS threshold voltage drops. This extraction allows the circuit to operate more efficiently at lower voltages while preserving the essential current comparison capability
Solution Approach 2:
The patent changes the operating parameters of the sensing circuit by transitioning from PMOS to NMOS technology, which enables operation at lower voltage levels. This parameter change directly reduces power consumption (P=IV) while maintaining the reliability of current comparison through the redesigned sensing amplifier architecture
3Loss of energy
If lower operating voltages are targeted, then power consumption is reduced, but PMOS transistors cannot be turned on due to voltage threshold limitations
Solution Approach 1:
Instead of attempting to operate PMOS transistors at low voltages (which fails due to threshold limitations), the patent inverts the approach by using NMOS transistors in the sensing amplifier. NMOS devices can be effectively turned on at lower gate-to-source voltages, enabling the circuit to achieve both low power consumption and proper transistor switching capability
Data Source
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AI summary
A non-volatile memory device with a current injection sensing amplifier is disclosed.