High-Side Signal Sensing Circuit with Active Current Mirror
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Solution Overview
Problem
Conventional high-side signal sensing circuits using resistors as voltage dividers suffer from poor accuracy due to temperature and process variations, making it difficult to control and sense load current, especially when the load is LEDs, as the resistance values affect the illumination and current distribution.
Innovation Solution
A high-side signal sensing circuit comprising a signal-to-current converter, a second transistor, and a resistor, where the signal-to-current converter generates a mirror current in response to an input signal, allowing the second transistor to receive and correct the mirror current, enabling precise sensing of the current through the output resistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If resistors are used as voltage dividers for high-side signal sensing, then the circuit structure is simple, but the measurement precision deteriorates due to temperature and process variations affecting resistance values
Solution Approach 1:
The patent replaces the passive resistor-based voltage divider with an active operational amplifier circuit that uses feedback to maintain precise voltage relationships. The op-amp actively compensates for variations, substituting the passive mechanical resistor system with an active electronic control system that achieves superior measurement precision.
Solution Approach 2:
The patent implements a feedback mechanism where the operational amplifier continuously monitors the voltage at its inputs and adjusts its output to maintain equal voltages at the inverting and non-inverting terminals. This feedback loop compensates for temperature and process variations, ensuring accurate load current sensing despite environmental changes.
2Use of energy by moving object
If voltage VH is adjusted to control LED illumination, then the power consumption changes, but the manufacturing precision deteriorates because resistance values affect current distribution
Solution Approach 1:
The operational amplifier circuit provides continuous feedback control that adjusts the voltage distribution in response to changes in VH. When the supply voltage changes, the feedback mechanism ensures that the voltage across the load remains precisely controlled, maintaining accurate current control regardless of power consumption variations.
Solution Approach 2:
The patent dynamically adjusts voltage parameters through the operational amplifier's output to compensate for changes in the supply voltage VH. By changing the output voltage parameter in response to input voltage variations, the circuit maintains precise current control through the load despite changes in overall power consumption.
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
This solution provides a precise method to sense the current through the output resistor, independent of temperature and process variations, ensuring accurate control and sensing of load current, even in high-voltage environments, enhancing the reliability of applications like battery management and LED backlight drivers.
Implementation Method 1
The signal-to-current converter has a first transistor generating a mirror current in response to an input signal
Implementation Method 2
The resistor generates an output signal in response to the mirror current
Data Source
AI summary
The present invention provides a high-side signal sensing circuit. The high-side signal sensing circuit comprises a signal-to-current converter, a second transistor and a resistor. The signal-to-current converter has a first transistor generating a mirror current in response to an input signal. The second transistor cascaded with the first transistor is coupled to receive the mirror current. The resistor generates an output signal in response to the mirror current. Wherein, the level of the output signal is corrected to the level of the input signal.