Sense Amplifier Circuit Stabilizes Memory Cell Current
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Solution Overview
Problem
Conventional non-volatile semiconductor memory devices experience unstable operating currents due to varying potential levels at the floating gate, affecting data reading accuracy and requiring circuit designs with large margins to compensate, which is not optimal for circuit structure.
Innovation Solution
A sense amplifier circuit with a current mirror configuration, including a selection gate transistor and a detection transistor, where the operating current of the selection gate transistor determines the output current, independent of the potential level at the detection transistor's gate, ensuring stable data output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circuit structure is designed with a sufficient margin to ensure a sufficiently large operating current of the memory cell, then data reading stability is improved, but circuit structure optimization is compromised
Solution Approach 1:
The invention introduces a selection gate transistor as an intermediary element between the detection transistor and the sense amplifier circuit. This selection gate transistor acts as a mediator that controls the operating current flowing through the memory cell, thereby stabilizing the current without requiring excessive margin in the overall circuit design. The selection gate transistor transforms the unstable potential level at the floating gate into a controlled current signal that can be reliably amplified.
Solution Approach 2:
The invention changes the control parameter from directly relying on the potential level at the floating gate to using the operating current of the selection gate transistor as the determining factor. By monitoring and amplifying the current through the selection gate transistor rather than directly amplifying voltage changes at the floating gate, the system achieves stable data reading with optimized circuit margins.
2Ease of operation
If the operating current is determined by the detection transistor's operating current, then data reading is simplified, but current stability deteriorates due to floating gate potential variations
Solution Approach 1:
The selection gate transistor serves as an intermediary that decouples the detection process from the floating gate potential variations. Instead of directly using the detection transistor's current which varies with floating gate potential, the selection gate transistor mediates by providing a controlled current path that is stabilized by its own gate control, thus simplifying reading while improving stability.
Solution Approach 2:
The invention segments the current control function into two parts: the detection transistor which senses the memory cell state, and the selection gate transistor which controls and stabilizes the operating current. This segmentation allows each transistor to perform its specific function optimally - detection without being directly affected by floating gate variations, and current control with stability.
Data Source
AI summary
A sense amplifier circuit for a non-volatile semiconductor memory device is used to output data written in a selected non-volatile memory cell and is constructed as a current mirror circuit including a first mirror transistor and a second mirror transistor of a mirror circuit. A selection gate transistor and a detection transistor of the selected non-volatile memory cell are included as part of a load circuit connected to a drain electrode of the second mirror transistor. The detection transistor has a drain electrode linked to a source electrode of the selection gate transistor. An operating current of the selection gate transistor is smaller than an operating current of the detection transistor, and an electric current output from the second mirror transistor is determined by the operating current of the selection gate transistor. This arrangement enables determination of the stable operating current of the memory cell irrespective of the state of a floating gate of the detection transistor. Data corresponding to the writing condition of the memory cell is thus stably output from the sense amplifier circuit, based on the stable operating current of the memory cell.