Floating Input Detection Circuit for Fast High-Impedance Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Floating input terminals in electronic devices can cause undesirable effects and indicate malfunctions, as existing detection methods either affect terminal impedance, require high voltage components, or slow down detection processes.
Innovation Solution
A data acquisition system with an analog front end (AFE) circuit and floating input detection circuitry that uses a common mode amplifier and programmable gain amplifier to quickly detect floating input terminals without impacting impedance or requiring high voltage components, employing coarse and fine detection methods to determine if an input terminal is floating based on signal amplitude comparisons to threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing detection methods are used to detect floating input terminals, then detection can be performed, but terminal impedance is affected or high voltage components are required or detection speed is slow
Solution Approach 1:
The patent introduces a common mode amplifier as an intermediary component that couples to the input terminal through high-impedance connections. This amplifier mediates between the input terminal and the detection circuitry, allowing floating input detection without directly loading the terminal. The common mode amplifier buffers the detection process, preventing impedance impact on the monitored terminal while still enabling accurate floating state detection through its output signal comparisons.
2Reliability
If existing detection methods are used to detect floating input terminals, then detection can be performed, but high voltage components are required
Solution Approach 1:
The patent replaces high voltage detection mechanisms with a low voltage common mode amplifier-based detection system. Instead of using high voltage comparators or voltage dividers that require high voltage components, the invention uses the common mode amplifier to sense voltage differences at low voltage levels. The detection is achieved by comparing the amplified common mode signal against reference voltages, eliminating the need for high voltage components while maintaining detection accuracy.
3Reliability
If existing detection methods are used to detect floating input terminals, then detection can be performed, but detection speed is slow
Solution Approach 1:
The patent implements preliminary action by continuously monitoring the common mode voltage at the input terminal through the common mode amplifier before a floating condition occurs or immediately upon occurrence. The amplifier is always active and ready, maintaining a continuous signal that reflects the terminal state. This eliminates the need for periodic sampling or sequential detection steps, enabling immediate detection of floating conditions as they occur, thus improving detection speed while maintaining accuracy.
Data Source
Figure 1~2
Figure 3~5
Figure 4
AI summary
A method for detecting a floating signal input terminal includes providing a common-mode input voltage to a first amplifier (204) coupled to the signal input terminal (234), and providing an output signal (230) generated by the first amplifier (204) to: a non-inverting input (222) of a second amplifier (202) coupled to the signal input terminal (234), an inverting input (220) of the second amplifier (202), coarse detection circuitry, and fine float detection circuitry. The method also includes comparing, by the coarse detection circuitry, the output signal (230) to a first threshold voltage, and determining the signal input terminal (234) to be not floating responsive to the comparing indicating that the output signal (230) is greater than the first threshold voltage.