Differential Voltage Detection Circuit for Near-Zero and Bipolar Inputs
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Solution Overview
Problem
Existing voltage detection circuits struggle to accurately detect a wide range of voltages, including both positive and negative voltages, while minimizing leakage current, particularly when detecting lithium-ion battery voltages between 0 V to 5 V, and may suffer from indeterminate operation near 0 V.
Innovation Solution
A fully differential voltage detection circuit with a selector comprising two MOS transistors in series, one with a normal threshold and one with a low threshold, and a capacitance couple drive unit, allowing for accurate detection of a wide voltage range by controlling the on and off states of switches using drive capacitors and selection signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional voltage detection circuit is used, then the circuit structure is simple, but the detection accuracy deteriorates when detecting voltages near 0 V and leakage current increases
Solution Approach 1:
The selector is divided into multiple selection units, each handling specific voltage ranges. This segmentation allows each unit to be optimized for its specific range, improving overall detection accuracy while controlling leakage current through specialized low-threshold transistors in each unit.
Solution Approach 2:
The patent changes the threshold voltage parameter of MOS transistors by using both normal-threshold and low-threshold transistors in the selection units. This parameter variation enables accurate detection near 0 V by selecting appropriate transistor threshold characteristics for different voltage ranges, while minimizing leakage current through the low-threshold design.
2Adaptability or versatility
If a selector with normal MOS transistors is used, then the device complexity is low, but the adaptability to wide voltage ranges deteriorates
Solution Approach 1:
The selector is segmented into multiple selection units with different transistor threshold characteristics. This segmentation enables the circuit to adapt to wide voltage ranges by activating appropriate units based on the input voltage level, while keeping each individual unit relatively simple in structure.
Solution Approach 2:
The selection units are designed to handle multiple voltage ranges by incorporating both normal-threshold and low-threshold MOS transistors. This multi-functionality allows the same basic unit structure to operate across different voltage conditions, improving adaptability without proportionally increasing complexity.
3Measurement precision
If the selector uses only normal MOS transistors, then the manufacturing process is simple, but the detection accuracy near 0 V deteriorates
Solution Approach 1:
The patent introduces low-threshold MOS transistors with modified threshold voltage parameters to improve detection accuracy near 0 V. These special transistors are integrated into specific selection units, allowing high-precision detection in critical voltage ranges while maintaining standard manufacturing processes for the overall circuit.
Solution Approach 2:
Low-threshold MOS transistors are selectively applied only in selection units where high-precision detection near 0 V is required, rather than throughout the entire circuit. This local quality approach improves detection accuracy where needed while keeping the rest of the manufacturing process simple and standardized.
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 circuit achieves accurate detection of both positive and negative voltages without leakage current, maintaining detection accuracy and expanding the input range, suitable for applications like battery monitoring ICs that require wide voltage detection.
Implementation Method 1
a capacitance couple drive unit that includes: a drive capacitor; and a drive unit that generates a drive signal for driving a gate of the at least one MOS transistor and supplies the drive signal to the gate of the at least one MOS transistor, and controls an on and off state of each of the plurality of switches by driving the gate of the at least one MOS transistor via the drive capacitor
Data Source
AI summary
A voltage detection circuit includes: switches each of which includes a MOS transistor capable of opening and closing between a pair of input nodes and a pair of output nodes; a capacitance couple drive unit having a drive unit; and a selector that is connected between the pair of input nodes, selects one of voltages of the pair of input nodes, and outputs a selection signal having a potential corresponding to a selected voltage. The drive unit generates the drive signal using the potential of the selection signal as a reference potential. The selector includes two MOS transistors connected in series between the pair of input nodes. One of the two MOS transistors is a normal MOS transistor having a normal threshold voltage. An other of the two MOS transistors is a low-threshold MOS transistor having a threshold lower than the normal threshold.