Trimmed Voltage Generator for Semiconductor Memory Devices
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Solution Overview
Problem
Semiconductor memory devices face challenges in generating accurate operating voltages that are not affected by external factors such as temperature and power supply voltage, especially as integration increases, requiring a reliable method to produce internal voltages without external influence.
Innovation Solution
A semiconductor memory device that stores information of accurate trimmed voltage in nonvolatile memory cells and uses a plurality of current sources to generate and control internal voltages, allowing it to output accurate trimmed voltages without relying on external voltages, through a voltage trimming unit, memory cell array, and trimming current generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external voltage is used to generate operating voltages, then voltage accuracy can be maintained, but the device becomes dependent on external voltage input and cannot operate independently
Solution Approach 1:
The patent applies preliminary action by measuring and storing the difference between internal and external voltages during a trimming phase before normal operation. The voltage difference information is saved in nonvolatile memory cells, allowing the device to compensate for voltage variations independently during normal operation without requiring continuous external voltage input.
Solution Approach 2:
The patent uses an intermediary approach by introducing a voltage trimming unit that acts as a mediator between the internal voltage generator and the external voltage source. This unit measures the voltage difference and uses stored trimming information to adjust the internal bandgap voltage, enabling the device to achieve accurate operating voltages independently without direct external voltage dependency.
2Use of energy by moving object
If internal voltage generation is used to reduce power consumption, then power efficiency improves, but voltage accuracy is affected by temperature and power supply variations
Solution Approach 1:
The patent implements feedback by using the stored voltage difference information from the trimming phase to continuously adjust and compensate for variations in the internally generated bandgap voltage. The voltage trimming unit uses the saved trimming data to correct temperature and power supply variations, maintaining voltage accuracy while operating independently with reduced power consumption.
3Adaptability or versatility
If voltage trimming using multiple current sources is implemented, then independent accurate voltage output is achieved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the voltage trimming function into separate components: a voltage trimming unit for measuring and controlling voltage differences, nonvolatile memory cells for storing trimming information, and a bandgap voltage reference unit for generating internal voltage. This modular segmentation allows independent operation with accurate voltage output while managing complexity through functional separation.
Data Source
AI summary
A semiconductor memory device including a trimmed voltage generator and a method of generating a trimmed voltage in the semiconductor memory device, in which the semiconductor memory device includes a voltage trimming unit, memory cell array, and a trimming current generator. The voltage trimming unit outputs a first trimming current control signal corresponding to a difference between a predetermined internal voltage and an external voltage supplied from outside of the semiconductor memory device in a trimming mode. The memory cell array stores the first trimming current control signal in the trimming mode and outputs a second trimming current control signal corresponding to the first trimming current control signal in a normal mode. The trimming current generator outputs a trimming current corresponding to the first trimming current control signal in the trimming mode and outputs a trimming current corresponding to the second trimming current control signal in the normal mode. The voltage trimming unit controls the internal voltage to be identical to the external voltage and outputs the controlled internal voltage as the trimmed voltage in response to the trimming current. The semiconductor memory device and the trimmed voltage generating method can output an accurate trimmed voltage without using a voltage supplied from outside in the normal operation.