Bulk-Driven Current-Sense Amplifier Low Voltage Operation
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Solution Overview
Problem
Conventional current-sense amplifiers in non-volatile memory devices often fail to operate successfully due to insufficient voltages, particularly when the operating voltage is low, leading to failed memory operations.
Innovation Solution
A bulk-driven current-sense amplifier is developed, comprising a differential amplifier and two drivers with PMOS transistors, where the first and second drivers form nodes with stabilized potentials based on currents flowing through memory units, allowing the differential amplifier to generate a voltage output, thereby increasing the range of read currents at low voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If conventional current-sense amplifier is used with low operating voltage, then power consumption is reduced, but the amplifier fails to generate sufficient stabilized voltages for reliable operation
Solution Approach 1:
The patent changes the operating parameters of the PMOS transistors by connecting the body to different potentials than the source, creating body effect that modifies the threshold voltage. This allows the amplifier to achieve sufficient voltage headroom for reliable operation while maintaining low supply voltage and power consumption. The body-bulk voltage difference adjusts the effective threshold voltage to enable proper amplification at low voltages.
2Device complexity
If conventional current-sense amplifier is used, then circuit structure is simple, but the stabilized voltages VMAT and VREF are insufficient at low operating voltages
Solution Approach 1:
The patent modifies the voltage parameters by utilizing body effect in PMOS transistors. By applying different body-bulk voltage differences to the input transistors, the effective threshold voltages are adjusted, which in turn adjusts the stabilized output voltages VMAT and VREF. This allows achieving higher stabilized voltages without increasing the supply voltage or complicating the circuit structure significantly.
3Stability of the object's composition
If body and source of PMOS are connected to form diode configuration, then gate voltage is stabilized according to current, but the required voltages VMAT and VREF become insufficient at low VDD
Solution Approach 1:
The patent changes the body potential parameter relative to the source potential for the PMOS transistors. By applying body-bulk voltage differences, the effective threshold voltage is modified, which allows the stabilized gate voltages to translate into higher VMAT and VREF voltages. This resolves the voltage headroom insufficiency while preserving the current-to-voltage stabilization function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The bulk-driven current-sense amplifier achieves higher stabilized voltages for VMAT and VREF, enabling successful memory operations even at low voltages, with VMAT and VREF reaching up to 350 mV when VDD is 0.5V, compared to conventional amplifiers which only reach 150 mV, thus improving the reliability of memory read operations.
Implementation Method 1
the first transistor has a drain coupled to a body of the first transistor and the first voltage input terminal of the differential amplifier to form a first node... the first and second nodes have stabilized first and second potentials, respectively, according to the current flowing through the first and the second memory unit
Data Source
AI summary
A bulk-driven current-sense amplifier and an amplifier operating method are disclosed. The bulk-driven current-sense amplifier includes a differential amplifier, a first driver, and a second driver. The first driver is coupled to the differential amplifier, and a first node is formed at a connectivity segment of the first driver. The second drive is coupled to the differential amplifier, and a second node is formed at a connectivity segment of the second driver. When a first switch of the first driver and a second switch of the second driver are turned on, the differential amplifier charges the first node and the second node. When the charging is completed, the first node and the second node respectively have a different stabilized potential according to currents separately flowing through a first memory unit of the first driver and a second memory unit of the second drive, and the differential amplifier generates a voltage.