Semiconductor Memory Internal Voltage Circuit Dynamics
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Solution Overview
Problem
Semiconductor memory devices face challenges in maintaining stable internal voltage levels during varying operational modes, leading to potential malfunctions due to fluctuating current dissipation, which existing internal voltage generating circuits are unable to address effectively.
Innovation Solution
An internal voltage generating circuit that includes a driving current generator, comparison voltage generator, and bulk bias controller, which control the bulk bias voltage and threshold voltage based on operational modes to manage current drivability and reduce current dissipation, featuring transistors and transmission gates to adjust voltage and current output in response to power-down, normal, and operating enable signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the first internal power supply voltage generating circuit is configured to have high current drivability and fast response speed for active mode operations, then current drivability and response speed are improved, but current dissipation increases during standby mode
Solution Approach 1:
The patent applies dynamics by making the circuit configuration changeable based on operational mode. The bulk bias controller dynamically adjusts the bulk bias voltage applied to the voltage driver transistor depending on whether the device is in active mode or standby mode, allowing the circuit to optimize its electrical characteristics for each operational state rather than being fixed
Solution Approach 2:
The patent changes the bulk bias voltage parameter to control the threshold voltage of the voltage driver transistor. By adjusting this parameter based on operational mode, the circuit achieves different current drivability levels - higher current capability in active mode and lower current dissipation in standby mode, directly addressing the contradiction between performance and energy consumption
2Productivity
If the bulk bias voltage is increased to improve current drivability during active operations, then current drivability is improved, but current dissipation increases during standby operations
Solution Approach 1:
The bulk bias controller dynamically switches the bulk bias voltage level based on the operational mode detected by the mode detector. During active operations, a higher bulk bias voltage is applied to enhance current drivability. During standby mode, the bulk bias voltage is reduced or removed, thereby minimizing current dissipation while maintaining necessary functionality
Solution Approach 2:
The patent utilizes parameter changes by varying the bulk bias voltage applied to the voltage driver transistor. This parameter adjustment directly controls the threshold voltage, enabling the circuit to achieve high current drivability when needed while reducing current dissipation during low-power operations, effectively resolving the contradiction
3Device complexity
If a single internal power supply voltage generating circuit is used for both active and standby modes, then device complexity is reduced, but the circuit cannot rapidly restore stable internal voltage when current dissipation varies
Solution Approach 1:
The patent segments the voltage generation function by separating the bulk bias control path from the main voltage generation path. The bulk bias controller and mode detector are added as independent control modules that manage the threshold voltage characteristics, allowing the main voltage driver to focus on voltage generation while the control path handles adaptive optimization for different operational modes
Solution Approach 2:
The mode detector provides feedback about the current operational state to the bulk bias controller, which then adjusts the bulk bias voltage accordingly. This feedback mechanism enables the circuit to automatically adapt to changing current dissipation conditions and rapidly restore stable internal voltage when transitioning between active and standby modes
Data Source
AI summary
An internal voltage generating circuit of a semiconductor memory device includes a driving current generator that controls the magnitude of a driving current and supplies a controlled driving current in response to signals activated according to an operational mode. A comparison voltage generator receives a reference voltage and an internal power supply voltage, outputs a differentially amplified comparison voltage in response to a voltage difference between the reference voltage and the internal power supply voltage, and operates according to the driving current. A bulk bias controller receives at least two voltages and selectively outputs a voltage as a bulk bias voltage in response to a power-down enable signal, a normal enable signal, and an operating enable signal. An internal voltage driver controls a threshold voltage in response to the bulk bias voltage, controls a current amount in response to the comparison voltage, and outputs the internal power supply voltage.