Segmented Switch Network Reduces Switching Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switch regulators experience undesirable levels of switching noise due to parasitic inductance, which can exceed component breakdown voltages and result in damage, necessitating a solution to reduce noise and improve supply ratings.
Innovation Solution
A low supply noise power stage arrangement is implemented using a first switch and a smaller second switch, where the second switch is triggered by a delayed signal offset from the control signal, allowing their switch time periods to overlap and extend the overall switching time, thereby reducing voltage overshoot and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If switch circuits are configured to turn on and turn off at relatively high rates to achieve relatively low overlap conduction losses, then productivity is improved, but object-generated harmful factors worsen due to undesirable levels of switching noise
Solution Approach 1:
The single switch is segmented into multiple parallel switches (first switch and second switch) with different sizes. This segmentation allows the switching action to be distributed across multiple devices, reducing the di/dt stress on parasitic inductance and thereby reducing switching noise while maintaining the overall switching rate for productivity.
Solution Approach 2:
The smaller second switch is activated before the main first switch turns off, creating an overlap period. This preliminary action of the second switch provides a gradual transition that reduces voltage overshoot and switching noise, while the overall switching cycle maintains the required high rate for low conduction losses.
2Productivity
If switching speed is increased to reduce overlap conduction losses, then productivity is improved, but object-generated harmful factors worsen due to exacerbated switching noise that can exceed breakdown voltages
Solution Approach 1:
By dividing the switching function across multiple parallel switches with different sizes, the rate of current change (di/dt) is reduced during switching transitions. This segmentation prevents excessive voltage overshoot caused by parasitic inductance while maintaining fast enough overall switching speed to minimize conduction losses.
Solution Approach 2:
The invention changes the parameter distribution by using switches of different sizes in parallel. The smaller switch handles part of the current with lower di/dt, reducing voltage overshoot, while the larger switch provides the main current path. This parameter differentiation allows fast switching without excessive noise.
3Device complexity
If a single large switch is used to handle full current, then device complexity is minimized, but object-generated harmful factors worsen due to high switching noise from parasitic inductance
Solution Approach 1:
The switch network is segmented into multiple parallel switches instead of a single large switch. This segmentation reduces the switching noise generated by parasitic inductance while the parallel configuration maintains relatively simple device structure. The different switch sizes optimize the balance between noise reduction and current handling capability.
Data Source
AI summary
In a general aspect, an apparatus can include a first switch configured to be coupled to a power source and configured to switch in response to an edge of a control signal. The apparatus can include delay circuit can be configured to produce a delay signal that has an edge corresponding to the edge of the control signal, the edge of the delay signal being offset from the edge of the control signal. The apparatus can also include a second switch can be configured to be coupled to the power source in parallel with the first switch and configured to switch in response to the edge of the delay signal, the second switch having a size smaller than a size of the first switch.