Trimmed Resistor Circuit Layout for Wide-Range Current Sensing
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Solution Overview
Problem
Conventional resistance devices with polysilicon elements face challenges in achieving a small temperature dependence and high accuracy in adjusting resistance values over a wide range while minimizing circuit area, leading to increased costs due to large numbers of resistors and complex configurations.
Innovation Solution
A resistance device with a reference resistor and series/parallel variable resistor circuits, each including resistors and trimming elements, allows for adjustable resistance values by configuring the circuits to satisfy specific expressions that ensure high accuracy and reduced circuit area, using polysilicon layers with controlled ion implantation for minimal temperature dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the minimum resistance value of the resistor connected in parallel to the fuse is decreased to adjust resistance value with high accuracy, then the resistance value adjustment accuracy is improved, but the sheet resistance value becomes constant due to polysilicon properties, limiting further reduction
Solution Approach 1:
The resistance device is divided into multiple resistance elements (first resistance element, second resistance element, third resistance element) with different resistance values. These segmented elements are connected in specific configurations (series and parallel combinations) to achieve a wide range of adjustable resistance values while maintaining high accuracy, overcoming the limitation of a single resistor's minimum resistance value.
Solution Approach 2:
The patent transitions from a single-dimension resistance adjustment (single resistor value) to multi-dimensional adjustment by combining multiple resistance elements with different resistance values (1R, 2R, 4R, 8R, etc.) in series and parallel configurations. This dimensional expansion allows achieving both high accuracy and wide adjustment range simultaneously.
2Adaptability or versatility
If the number of resistors connected in parallel is increased to decrease the minimum resistance value, then the resistance value range is extended, but the circuit area increases leading to increased cost
Solution Approach 1:
The patent employs dynamic trimming elements (fuses) that can be selectively connected or disconnected during the trimming process. This dynamic configuration allows the resistance value to be adjusted from high to low ranges by selectively engaging different resistance elements, achieving wide adjustment range without permanently increasing circuit area through fixed parallel resistor networks.
Solution Approach 2:
Instead of using a large number of resistors connected in parallel to achieve low resistance values, the patent segments the resistance adjustment into multiple stages using series and parallel combinations of resistance elements with different base values (1R, 2R, 4R, 8R, etc.), thereby reducing the total number of components and circuit area.
3Adaptability or versatility
If the length L of the unit resistor is decreased and width W is increased to decrease the minimum resistance value, then the resistance value range is extended, but the number of series resistors increases leading to increased circuit area
Solution Approach 1:
The patent changes the resistance value parameter by using resistance elements with different base resistance values (1R, 2R, 4R, 8R, 16R, etc.) rather than relying on geometric changes (length and width) of a single unit resistor. This parameter diversification allows achieving wide resistance range adjustment without increasing the number of series resistors or circuit area.
4Stability of the object's composition
If polysilicon layer with controlled ion implantation is used to achieve small temperature dependence, then the temperature stability is improved, but the sheet resistance value falls within a certain range, limiting resistance value adjustment
Solution Approach 1:
The patent segments the resistance device into multiple resistance elements, each with optimized ion implantation for small temperature dependence. By combining these elements in series and parallel configurations, the device maintains the temperature stability of individual polysilicon elements while achieving a wide overall resistance value range through selective combination.
Solution Approach 2:
The patent creates a composite resistance structure by combining multiple polysilicon resistance elements with different resistance values (achieved through different ion implantation doses or geometric dimensions) into a unified device. This composite structure maintains the advantageous temperature characteristics of polysilicon while expanding the adjustable resistance range.
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 enables resistance value adjustment over a wide range with high accuracy and reduced circuit area, minimizing errors and maintaining low temperature dependence, thus reducing the cost and complexity of semiconductor chip production.
Implementation Method 1
the dose amount at the time of ion-implanting impurities with respect to the polysilicon
Data Source
AI summary
To provide a resistance device which has a small temperature dependence, in which a resistance value is adjustable in a wide range of from a high resistance value to a low resistance value, and which has a small circuit area, and to provide a current detection circuit including the resistance device. The resistance device is to be connected between two terminals, and a resistance value thereof is variable, the resistance device including: a reference resistor; a series variable resistor circuitry including at least one parallel variable resistor circuit which is connected in series to each other, and which each includes a resistor and a trimming element connected in parallel to the resistor; and a parallel variable resistor circuitry including at least one series variable resistor circuit which is connected in parallel to each other, and which each includes a resistor and a trimming element connected in series to the resistor.