Voltage Generation Circuit for Semiconductor Memory
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Solution Overview
Problem
Conventional non-volatile semiconductor memory voltage generation circuits face challenges in achieving accurate and constant voltage stepping due to offset voltages between differential amplifiers and dispersion in resistance values, leading to inconsistent voltage step-up and errors in set voltages.
Innovation Solution
A voltage generation circuit design that eliminates the need for a pair of differential amplifiers, using a binary code for lower bits and a thermometer code for upper bits, along with a redundancy circuit to replace abnormal resistive elements, ensuring high accuracy and constant voltage step width by minimizing the effect of resistance value dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a voltage limiter circuit using an R-2R resistance ladder and two differential amplifiers is employed to set variable voltages, then the voltage setting capability is provided, but offset occurs between the two differential amplifiers due to dispersion in processes, preventing desired voltage step
Solution Approach 1:
The patent extracts and eliminates one of the two differential amplifiers from the conventional voltage limiter circuit. By removing the second differential amplifier, the circuit avoids the offset problem between two amplifiers while maintaining voltage setting capability through a simplified architecture using a single differential amplifier, R-2R resistance ladder, and gate transistors.
Solution Approach 2:
Instead of using two differential amplifiers to achieve voltage setting, the patent inverts the approach by using a single differential amplifier combined with gate transistors that directly control the R-2R resistance ladder. This inversion of the conventional architecture eliminates the offset issue while achieving the same functional goal.
2Ease of operation
If two differential amplifiers are used in the voltage limiter circuit, then voltage setting is achieved, but offset occurs due to dispersion in processes, leading to inability to obtain desired voltage step
Solution Approach 1:
The patent removes one differential amplifier from the circuit, extracting the source of offset errors. This reduction in component count eliminates the reliability issue caused by mismatch between two amplifiers while preserving the essential voltage setting function through the remaining single amplifier and gate transistor configuration.
3Adaptability or versatility
If a conventional voltage generation circuit with two differential amplifiers is used, then voltage setting capability is provided, but offset voltages and resistance value dispersion cause inconsistent voltage step-up
Solution Approach 1:
The patent extracts and eliminates the second differential amplifier that contributes to offset voltages. By using only one differential amplifier with gate transistors controlling the R-2R ladder, the circuit achieves voltage setting capability while eliminating the measurement precision errors caused by amplifier offsets and resistance dispersion.
Solution Approach 2:
The patent changes the circuit parameters by reducing the number of differential amplifiers from two to one, and by using gate transistors to control the resistance ladder. This parameter change fundamentally alters the error characteristics of the circuit, eliminating offset voltages and improving voltage step precision.
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 solution provides a high-accuracy voltage generation circuit with a constant voltage step width, effectively addressing the issues of offset voltages and resistance value dispersion, ensuring stable and precise voltage stepping in non-volatile semiconductor memory systems.
Implementation Method 1
a charge pump circuit that outputs voltage by stepping up the voltage with the control signal
Implementation Method 2
a voltage setting circuit that has a plurality of resistive elements and a plurality of gate transistors connected to a plurality of the resistive elements and gradually sets voltage by switching a plurality of the gate transistors to switch a combination of a plurality of the resistive elements
Implementation Method 3
a differential amplifier that has two input terminals and one output node, one input terminal is connected to the reference voltage that is generated by the standard voltage generation circuit, another input terminal is connected to the minimum voltage setting circuit and the voltage setting circuit, and the output node shows the result of the difference voltage of these two inputs
Data Source
AI summary
The voltage generation circuit having a standard voltage generation circuit, a reference voltage, a minimum voltage setting circuit, and a voltage setting circuit that gradually sets voltage by switching a plurality of the gate transistors to switch a combination of resistive elements. The voltage generation circuit includes a differential amplifier that has one input terminal connected to the reference voltage generated by the standard voltage generation circuit and another input terminal connected to the minimum voltage setting circuit. The differential amplifier has an output node showing the result of a difference voltage of the inputs. The voltage generation circuit includes a pump control circuit that outputs a control signal controlling a charge-pump motion, based on the differential voltage, and a charge pump circuit that sets up and outputs the voltage by the control signal.