Matrix Switch Circuit With Constant MOSFET ON-Resistance
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Solution Overview
Problem
Existing matrix switches using MOSFETs suffer from inaccurate and variable ON-resistance, leading to measurement errors due to body-diodes and voltage changes, which affect the reliability and consistency of telemetry channel inspections.
Innovation Solution
A switching circuit design utilizing a back-to-back connection of N-type MOSFETs with a voltage maintaining unit to maintain constant ON-resistance by adjusting the gate voltage based on source voltage changes, ensuring consistent operation as a bidirectional switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a MOSFET is used as a switching element in a matrix switch, then the switching function is achieved, but the ON-resistance varies due to body-diode effects and voltage changes, causing measurement errors
Solution Approach 1:
The patent divides the switching element into two separate MOSFETs (first and second switching elements) connected in series. This segmentation allows independent control of each element's gate voltage, enabling compensation for body-diode effects and voltage variations to maintain consistent ON-resistance across different switching paths
Solution Approach 2:
The patent dynamically adjusts the gate voltage of the first switching element based on the source voltage to compensate for variations. By changing the gate voltage parameter in response to voltage changes, the ON-resistance is maintained constant despite variations in operating conditions
2Measurement precision
If the gate voltage is adjusted to maintain constant ON-resistance, then measurement accuracy improves, but the circuit complexity increases due to additional voltage maintaining components
Solution Approach 1:
The patent implements a feedback mechanism where the gate voltage of the first switching element is adjusted based on the source voltage. This feedback loop automatically compensates for voltage variations and body-diode effects, maintaining constant ON-resistance without requiring complex external control circuits
Solution Approach 2:
The voltage maintaining unit serves multiple functions: it adjusts gate voltage to compensate for body-diode effects, maintains constant ON-resistance, and operates bidirectionally. This multi-functionality reduces the need for separate circuits for each function, thereby limiting the increase in overall circuit complexity
3Productivity
If the ON-resistance is kept low to improve signal transmission, then the switching performance improves, but the resistance varies across different switching circuit blocks, causing inconsistency
Solution Approach 1:
The patent dynamically adjusts the gate voltage parameter of the first switching element based on the source voltage to maintain constant ON-resistance. This parameter change compensates for variations across different switching circuit blocks, ensuring uniform resistance while maintaining low resistance values for high switching performance
Solution Approach 2:
The patent applies different gate voltage adjustments to different switching elements based on their specific operating conditions. By optimizing each element's gate voltage locally, the system achieves uniform ON-resistance across all switching paths while maintaining low resistance values for high-speed operation
Data Source
AI summary
According to various exemplary embodiments of the present disclosure, a switching circuit is applied so as not to cause a problem due to body-diode and maintains a resistance (ON-resistance) between a drain region and a source region to be constant by adjusting a voltage of the gate region in accordance with the voltage change of the source region. Further, the matrix switch is applied so that even though the temperature changes in accordance with the switching circuit block (row/column), the change in the ON-resistance is small.