Latch Sense Amplifier Without Reference Current Matching
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Solution Overview
Problem
Existing sense amplifiers for flash memory require a reference current for precise detection of bitcell currents, leading to increased power consumption and complexity, especially in large data buses where matching mirrored currents to reference currents becomes difficult, and occupy significant silicon area due to additional circuitry and transistors.
Innovation Solution
A sense amplifier design that eliminates the need for a current mirror and reference current generator, using a single control signal (EN) and mismatched NMOS transistors to simplify read logic and reduce silicon area, thereby reducing power consumption and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference current generator and current mirror are used for precise detection, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts and eliminates the reference current generator and current mirror components from the sense amplifier circuit. By removing these complex components, the circuit achieves precise detection of bitcell currents without requiring traditional current matching mechanisms, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The sense amplifier circuit uses its own internal transistor characteristics and operating conditions to perform detection, eliminating the need for external reference current generators. The circuit serves itself by using the bitcell current directly to control the pass transistor, creating a self-referencing detection mechanism that simplifies the overall circuit architecture.
2Measurement precision
If additional circuitry is added for current matching, then measurement precision is improved, but silicon area increases
Solution Approach 1:
The patent removes the additional circuitry required for current matching, including reference current generators and current mirrors. This extraction of unnecessary components directly reduces the silicon area occupied by the sense amplifier while maintaining the ability to perform precise current detection through the simplified direct control mechanism.
3Reliability
If multiple control signals are used for read logic, then operational reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple control signals into a single control signal that directly controls the pass transistor. This consolidation reduces the number of control signals required while maintaining operational reliability, as the single control signal effectively manages the detection operation without the complexity of multiple coordinated signals.
Data Source
AI summary
A sense amplifier (100) includes first and second inverters (112 and 113). The first inverter has an input terminal (116) and an OUT_B output node and a first transistor (124). The second inverter (113) has an input terminal (115) and an OUT output node and a second transistor (125). The OUT_B output node of the first inverter is coupled to an input terminal of the second inverter, and the OUT node of the second inverter is coupled to an input terminal of the first inverter. The sense amplifier does not use a reference current; therefore, the sense amplifier does not need a reference current generator. The sense amplifier needs only one enable signal to reset a latch (110) of the sense amplifier. When coupled to a non-volatile memory element, voltages at the output nodes are indicative of a logic level of a bit stored in the non-volatile memory element.