Current Sense Amplifier With Common-Mode Voltage Suppression
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Solution Overview
Problem
Current sense amplifiers struggle to handle a wide range of DC voltage inputs, particularly on the high side, and require high speed, high precision, and low temperature drift for effective motor control.
Innovation Solution
A current sense amplifier with a common mode voltage suppressor that includes a voltage division resistor and transistors to suppress common mode voltage, allowing it to operate with a wide range of DC voltages and adjust gain or output offset voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a current sense amplifier is used on the high side to detect current through a current detection resistor, then the amplifier can handle higher voltage inputs, but the common mode voltage becomes much higher than the power supply voltage of the amplifier itself, making it difficult to set gain or output offset voltage
Solution Approach 1:
The patent introduces a common mode voltage suppressor as an intermediary component between the high voltage input and the amplifier. This suppressor includes a voltage division resistor that divides the common mode voltage, and transistors that subtract the divided common mode voltage from the input signal, enabling the amplifier to process high voltage inputs while maintaining proper operating levels
Solution Approach 2:
The patent changes the voltage level parameter by using a voltage division resistor to scale down the common mode voltage. By dividing the high common mode voltage into a lower level, the system can handle high voltage inputs while the amplifier operates within its acceptable voltage range, allowing proper gain and offset voltage setting
2Measurement precision
If the common mode voltage is not suppressed, then the circuit can operate with high input voltages, but the gain and output offset voltage cannot be properly set
Solution Approach 1:
The common mode voltage suppressor acts as an intermediary that processes the input signal before it reaches the amplifier. By using voltage division resistors and transistors to subtract the common mode component, the circuit achieves precise current detection while managing the complexity through a dedicated suppression stage
Solution Approach 2:
The patent segments the signal processing into distinct functional blocks: a common mode voltage suppressor stage that handles voltage level management, and an amplifier stage that performs precise current detection. This segmentation allows each stage to be optimized independently, achieving measurement precision while containing overall complexity
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 amplifier effectively suppresses common mode voltage, enabling it to handle a wide range of DC inputs and set gain or output offset voltage, ensuring high precision and low temperature drift for motor control.
Implementation Method 1
a voltage division resistor, the upper side voltage and the lower side voltage being supplied to the two ends thereof, and a division voltage being obtained
Implementation Method 2
a first transistor, the upper side voltage being input to one end thereof, and the other end thereof being connected to a predetermined power supply; and a second transistor, the lower side voltage being input to one end thereof, and the other end thereof being connected to a predetermined power supply
Data Source
AI summary
[Problem to be solved] The disclosure is to deal with a wide range of DC voltages in the input.[Solution] In a current sense amplifier 100, an upper side voltage and a lower side voltage of a current detection resistor 2 are input thereto, and an output corresponding to a difference between the upper side voltage and the lower side voltage is obtained. A common mode voltage suppressor 12 includes: voltage division resistors R6a and R6b, the upper side voltage and the lower side voltage being supplied to the two ends thereof, and a division voltage being obtained; a first transistor M1, the upper side voltage being input to one end thereof, and the other end thereof being connected to a predetermined power supply; and a second transistor M2, the lower side voltage being input to one end thereof, and the other end thereof being connected to a predetermined power supply. A control end of the first transistor M1 and a control end of the second transistor M2 are commonly connected and the division voltage is input thereto.