Internal Voltage Trimming Circuit Using Clock Counting
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Solution Overview
Problem
Conventional internal voltage trimming circuits in semiconductor memory devices, such as NAND-type flash memory, face challenges in precise voltage adjustment due to high consumption current, large resistor values, and variations in resistors and comparators, leading to decreased voltage accuracy and increased occupied space.
Innovation Solution
An internal voltage trimming circuit that uses a clock generator to count changes in current flowing through a transistor, allowing for precise control of internal voltages without a resistive voltage divider or comparator, utilizing a current source to adjust offset currents and selectively operate transistors for accurate voltage trimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a voltage trimming circuit using a resistor ladder circuit and a comparator is used to control and adjust internal voltages, then voltage adjustment capability is improved, but consumption current increases and voltage accuracy decreases due to process variations of the comparator and resistors
Solution Approach 1:
The patent extracts and removes the comparator and resistive voltage divider from the trimming circuit. Instead of using a comparator to detect voltage levels, the invention uses a capacitor-based voltage storage and comparison mechanism where the voltage to be trimmed is directly compared against a reference voltage through capacitor charging, eliminating the need for resistive division and comparative detection that cause accuracy issues.
Solution Approach 2:
The patent replaces the electrical/mechanical resistor-ladder and comparator system with an electrical capacitor-based system. The mechanical analogy would be replacing a physical ruler and visual comparison (resistor ladder + comparator) with an electrical timing-based measurement (capacitor charging time), where the trimming is achieved through controlled capacitor charging rather than resistive voltage division.
2Ease of operation
If a voltage trimming circuit using a resistor ladder circuit and a comparator is used, then voltage adjustment capability is improved, but the occupied space increases due to large resistor values
Solution Approach 1:
The patent extracts and removes the resistor ladder circuit from the trimming circuit. Instead of using multiple resistors with large resistance values that occupy significant space, the invention uses capacitors with much smaller physical dimensions to achieve the same voltage trimming function, dramatically reducing the occupied area.
Solution Approach 2:
The patent changes the fundamental parameter from resistance to capacitance. By using capacitive elements instead of resistive elements, the circuit achieves voltage trimming through charge storage and timing characteristics rather than resistive voltage division, allowing for much more compact implementation while maintaining the required adjustment capability.
3Ease of operation
If a BIST circuit with a resistor dividing circuit and comparator is used for voltage trimming, then voltage adjustment is possible, but consumption current becomes extra current for the charge pump and voltage accuracy decreases
Solution Approach 1:
The patent extracts and removes the resistive voltage divider from the BIST circuit. Instead of continuously drawing current through resistors to establish voltage division ratios, the invention uses capacitors that only draw current during the trimming operation itself, eliminating the continuous extra current consumption that burdens the charge pump.
Solution Approach 2:
The patent implements periodic action by using capacitive charging cycles instead of continuous resistive current flow. The voltage trimming is performed through periodic capacitor charging and comparison operations, where current is drawn only during the necessary trimming intervals rather than continuously, significantly reducing the average consumption current from the charge pump.
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
This solution enables precise internal voltage trimming with reduced consumption current, eliminating the need for resistive dividers and comparators, thereby improving voltage accuracy and reducing occupied space while maintaining high resolution.
Implementation Method 1
a clock generator for generating a clock according to current flowing through a transistor of a power supply current source for the clock generator
Implementation Method 2
an internal voltage generator for generating internal voltage based on the reference voltage and a charge pump
Data Source
AI summary
TASK: to provide an internal voltage trimming circuit having a simple configuration and operated by a consumption current smaller than that using a comparator. MEANS FOR SOLVING THE PROBLEM: An internal voltage trimming circuit comprises a trimming controller using a change in a counting value of a clock according to a current flowing through a transistor of a power supply current source for a clock generator to trim an internal voltage generated by an internal voltage generator. The trimming controller counts a first counting value of the clock when a predetermined reference voltage is applied to a control terminal of the transistor and a second counting value of the clock when the internal voltage is applied to the control terminal of the transistor and controls the internal voltage generated by the internal voltage generator to substantially coincide the second counting value with the first counting value.