Laminated Current Detection Circuit for Accurate Shunt Resistor Measurement
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Solution Overview
Problem
Current semiconductor devices with current detection circuits face challenges in achieving accurate current detection due to variations in shunt resistor resistance values, leading to errors and requiring complex analog control or expensive trimming methods, while also seeking to miniaturize the system with low-resistance shunt resistors in a small area.
Innovation Solution
A semiconductor device with a current detection circuit that includes a shunt resistor, a voltage division ratio adjustment resistor, and a selection circuit, where the selection circuit selects a voltage division point based on the shunt resistor's resistance value to output a detected voltage, using MOSFETs and trimming elements like Zener diodes or fuses to adjust the voltage division ratio, and laminating the shunt resistor on the voltage division ratio adjustment resistor through an interlayer insulating film to reduce area occupancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a low-resistance shunt resistor is used to reduce power loss, then power consumption is reduced, but the resistance value varies more due to manufacturing factors causing detection errors
Solution Approach 1:
The patent changes the resistance parameter by using a low-resistance shunt resistor (0.1Ω or less) to reduce power loss, while compensating for the resulting manufacturing variation through voltage division ratio adjustment. This allows achieving both low power consumption and acceptable detection accuracy.
Solution Approach 2:
The patent implements a feedback mechanism by measuring the actual voltage across the shunt resistor and comparing it with the expected value. The selection circuit then selects appropriate trimming resistors to compensate for deviations, creating a closed-loop system that maintains detection accuracy despite low shunt resistance.
2Measurement precision
If trimming is performed on the shunt resistor to correct resistance value variations, then detection accuracy is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent segments the trimming function into multiple discrete trimming resistors (first trimming resistor, second trimming resistor, etc.) that can be independently selected. This segmentation allows precise adjustment of the voltage division ratio without requiring complex continuous control circuits.
Solution Approach 2:
The patent makes the voltage division ratio dynamic by allowing selection among multiple fixed ratio options based on the actual shunt resistor value. The selection circuit dynamically chooses the appropriate trimming resistor combination to compensate for manufacturing variations.
3Measurement precision
If a voltage division ratio adjustment resistor is added to correct detection errors, then measurement precision is improved, but the area occupied by the current detection circuit increases
Solution Approach 1:
The patent transitions from a planar layout to a three-dimensional stacked architecture. The shunt resistor is placed in a lower layer while the voltage division ratio adjustment resistor and selection circuit are placed in an upper layer, effectively utilizing the vertical dimension to reduce the footprint area.
Solution Approach 2:
The patent implements a nested structure where the voltage division ratio adjustment resistor is positioned directly over the shunt resistor in the vertical stacking arrangement. This nesting allows the adjustment resistor to occupy the same horizontal footprint as the shunt resistor without increasing the overall circuit area.
4Adaptability or versatility
If multiple trimming resistors with different voltage division ratios are used to compensate for resistance variations, then adaptability is improved, but the device complexity increases
Solution Approach 1:
The patent makes the voltage division ratio adjustment resistor multi-functional by designing it to provide multiple fixed voltage division ratios (e.g., 0.5, 0.6, 0.7, 0.8, 0.9, 1.0). This single component structure serves multiple compensation purposes, replacing what would otherwise require multiple separate trimming circuits.
Data Source
AI summary
Current detection circuit of a semiconductor device provided with a shunt resistor, a voltage division ratio adjustment resistor and a selection circuit which selects a voltage division ratio of the latter and has enhancement type MOSFETs and Zener Zaps as trimming elements. One of the Zener Zaps is trimmed and a divided voltage of the voltage division ratio adjustment resistor connected in parallel with the shunt resistor is outputted. The detected voltage in which variation of the resistance of the shunt resistor has been cancelled is therefore outputted. As the shunt resistor and the voltage division ratio adjustment resistor are laminated together, it is possible to obtain a current detection circuit with a small area, which can detect a current flowing into a shunt resistor with high accuracy.