Grouped Resistor Trimming Circuit for Precise Switchable Resistance
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Solution Overview
Problem
Existing resistor trimming devices face precision issues due to resistor mismatching, particularly with binary and thermometer codes, leading to difficulties in achieving precise circuit characteristics, especially with increasing bits.
Innovation Solution
A resistor trimming device that divides a single adjustable resistor string into multiple groups, using a decoder to generate group and trimming thermometer codes, reducing the resistance faced by switches and allowing direct input of binary or original thermometer codes for precise resistance adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single adjustable resistor element with binary code is used, then the circuit can achieve current source and power source adjustment, but resistor matching becomes difficult and precision decreases as the number of bits increases
Solution Approach 1:
The patent divides a single adjustable resistor element into multiple adjustable resistor string groups (first group, second group, third group, etc.). Each group contains a subset of the total resistors and switches. This segmentation reduces the number of resistors that need to be matched within each group, thereby improving resistor matching precision while maintaining the overall adjustment capability through coordinated control of all groups.
2Measurement precision
If a single adjustable resistor element with thermometer code is used, then the trimming resistance can be adjusted from 0 to N*R, but as the number of bits increases, it becomes difficult to choose switches to turn on/off and circuit precision is affected
Solution Approach 1:
The patent segments the single adjustable resistor element into multiple adjustable resistor string groups, where each group contains a portion of the total switches and resistors. This segmentation reduces the number of switches that need to be controlled simultaneously within each group, simplifying the control complexity while maintaining precise trimming capability through the coordinated operation of all groups.
Solution Approach 2:
The patent introduces a group dimension by organizing resistors and switches into multiple groups. Instead of controlling all switches in a single long string, the system now has two dimensions of control: which group to activate and which switches within that group to activate. This dimensional organization reduces the complexity of switch selection and control.
3Adaptability or versatility
If the resistance of the parallel resistor faced by a switch is large, then the adjustable resistor element can provide wide resistance range, but it becomes harder to make the turn on resistor and turn off resistor meet design rules
Solution Approach 1:
The patent divides the resistor string into multiple groups, which effectively reduces the resistance value that each individual switch needs to handle in parallel. By segmenting the total resistance into smaller portions across groups, the parallel resistance faced by each switch is reduced, making it easier to meet the design rules for turn-on and turn-off resistors while still achieving a wide overall resistance range through combination of all groups.
Data Source
AI summary
A resistor trimming device comprising a resistor trimming unit is provided, which divides a single one adjustable resistor string into a plurality of adjustable resistor string groups, so that a resistance of the parallel resistor faced by a switch can be effectively reduced, and a design of the on-resistance and off-resistance of the switch can comply with a general design rule. In addition, the resistor trimming device provided further comprises a decoder. When trimming the overall resistance of an electronic device, a user can directly input a binary code or an original thermometer code used in the adjustable resistor string being not grouped, without knowing an encoding manner, and then, the decoder generates a trimming thermometer code and a group code to control a main switch and switches in the multiple adjustable resistor string groups being the grouped from the adjustable resistor string.