Dynamic Level Shift Circuit for Stable Current Detection
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Solution Overview
Problem
Current current sense amplifier circuits face challenges in maintaining stable input voltages due to fluctuations in common mode voltage, particularly when the level shift amount is constant, leading to voltage fluctuations at the input terminal, which can be exacerbated by power supply voltage fluctuations.
Innovation Solution
A current detection circuit incorporating a current sense amplifier and a level shift circuit that dynamically adjusts the level shift amount by controlling currents through resistors connected to the operational amplifier's input nodes based on the voltage of the shunt resistor node, allowing for variable level shifting to maintain stable input voltages despite common mode voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a constant current is used for level shifting in the current sense amplifier, then the level shift amount remains constant, but the input terminal voltage fluctuates due to common mode voltage changes
Solution Approach 1:
The patent applies the Dynamics principle by transitioning from a static constant current level shifting mechanism to a dynamic variable current mechanism. The level shift circuit now varies the level shift amount according to the common mode voltage detected from the shunt resistor, allowing the system to adapt to changing voltage conditions and maintain stable input terminal voltages despite power supply fluctuations.
Solution Approach 2:
The patent implements feedback by detecting the common mode voltage at the shunt resistor and using this information to adjust the level shift amount. The level shift circuit receives feedback about the common mode voltage level and dynamically adjusts its output to compensate for voltage fluctuations, ensuring stable operation of the current sense amplifier across varying power supply conditions.
2Reliability
If a wide input voltage range operational amplifier is used to accommodate common mode voltage fluctuations, then voltage stability is maintained, but device complexity and cost increase
Solution Approach 1:
The patent introduces an intermediary level shift circuit between the shunt resistor and the operational amplifier inputs. This intermediary component performs the function of voltage stabilization by dynamically adjusting the level shift amount according to common mode voltage, thereby protecting the operational amplifier from wide voltage fluctuations and allowing the use of simpler, lower-voltage-rated components.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the level shift amount parameter based on the common mode voltage level. Instead of using an operational amplifier with a fixed wide voltage range, the system changes the level shift parameter in real-time to maintain stable input voltages, allowing the use of operational amplifiers with narrower, more cost-effective voltage ranges.
Data Source
AI summary
A current detection circuit includes an operational amplifier, a current sense amplifier including a first resistor and a second resistor, and a level shifter. The first resistor is provided between one end of a shunt resistor and a first input node of the operational amplifier. The second resistor is provided between the other end of the shunt resistor and a second input node of the operational amplifier. The level shifter controls voltages of the first input node and the second input node by controlling, according to a voltage at the one end of the shunt resistor, currents supplied to the first input node and the second input node.