Balancing Current in Parallel Switch Circuits Using Kelvin Source Resistors
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Solution Overview
Problem
Parallel switching devices in electronic systems often experience current and power unbalance due to manufacturing process variations and layout asymmetry, leading to inefficient current distribution and potential oscillations during switching.
Innovation Solution
The introduction of a resistive element, specifically a Kelvin source resistor, between the source terminals and control nodes of parallel switch circuits, which balances transient current and power by adjusting the gate-source voltage difference between transistors, thereby counteracting threshold voltage variations and preventing oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If parallel switching devices are used to increase power capacity, then power capacity is improved, but current and power unbalance occurs due to manufacturing variations and layout asymmetry
Solution Approach 1:
The patent applies parameter changes by carefully selecting and adjusting the resistance value of the balancing resistor based on process corners (minimum, nominal, maximum parameters) to optimize current distribution. The resistance value is determined through simulation across different process variations to achieve optimal current balancing while preventing oscillations
Solution Approach 2:
The patent introduces a balancing resistor as an intermediary element connected to the source terminal of each parallel switching device. This resistor acts as a mediator that equalizes the current distribution by creating voltage drops that compensate for threshold voltage variations and layout asymmetries, thereby improving current balancing without requiring complex active control circuits
2Manufacturing precision
If active compensation devices are added to balance current, then current balancing is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex active compensation circuits with simple passive resistors that are inexpensive and easy to implement. The balancing resistors are standard components that can be easily integrated into the power circuit without requiring complex control logic or additional active devices, thereby reducing overall device complexity while achieving effective current balancing
3Manufacturing precision
If resistive elements are added to balance transient current, then current balancing is improved, but oscillation may be caused in the transient current
Solution Approach 1:
The patent carefully selects the resistance value based on process corners and simulates transient behavior to ensure the resistor balances current without causing oscillations. The resistance is optimized to provide sufficient damping to prevent oscillatory behavior while maintaining effective current balancing across all process variations
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 effectively balances transient current and power among parallel switch modules, reducing power loss differences and preventing oscillations, thereby enhancing the overall efficiency and stability of the power circuit during switching operations.
Implementation Method 1
At least one of a first source terminal of the first switch circuit and a second source terminal of the second switch circuit is coupled to the second control node with a resistive element having a specific resistance
Implementation Method 2
the resistive element is configured not to cause oscillation in the transient current flowing through the first switch circuit and the second switch circuit when the first and second switch circuits are switched on/off
Data Source
AI summary
Aspects of the disclosure provide a power circuit that includes a first switch circuit in parallel with a second switch circuit. The first switch circuit and the second switch circuit are coupled to a first control node, a second control node, a first power node and a second power node via interconnections. The power circuit receives a control signal between the first control node and the second control node to control a current flowing from the first power node to the second power node through the first switch circuit and the second switch circuit. At least one of a first source terminal of the first switch circuit and a second source terminal of the second switch circuit is coupled to the second control node with a resistive element having a specific resistance.