Shared On-Die Decoupling Capacitor for High-Speed Interfaces
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Solution Overview
Problem
In semiconductor processor devices, providing separate decoupling capacitors for each high-speed interface results in waste of die area and unnecessary cost due to unused interfaces in different device variants.
Innovation Solution
A single decoupling capacitor is shared between mutually exclusive interfaces, with internal connection members such as bond wires connecting the capacitor to the appropriate interface, allowing the capacitor value to be adjusted based on the interface's requirements, and additional capacitance can be permanently connected when needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate decoupling capacitors are provided for each high-speed interface, then noise reduction performance is improved, but die area and cost increase due to unused capacitors in variants with fewer interfaces
Solution Approach 1:
The patent implements a shared decoupling capacitor structure where a single capacitor serves multiple high-speed interfaces through selective connection mechanisms. The capacitor is connected to a common node that can be selectively coupled to different interface pairs (e.g., first interface pair, second interface pair) based on which interfaces are active in a given device variant. This universal approach allows one capacitor to perform the noise reduction function for any active interface pair, eliminating the need for separate dedicated capacitors for each interface while maintaining the necessary noise isolation performance.
2Reliability
If separate decoupling capacitors are provided for each high-speed interface, then noise reduction performance is improved, but manufacturing cost increases due to unnecessary components
Solution Approach 1:
The shared capacitor architecture reduces component count and manufacturing complexity. By using one capacitor that can be selectively connected to different interface pairs through bond wires or other connection members, the manufacturing process is simplified compared to providing separate capacitors for each interface. The selective connection mechanism allows the same capacitor to serve different interfaces in different device variants, reducing inventory complexity and assembly steps.
Solution Approach 2:
The patent merges multiple decoupling functions into a single physical capacitor component. Instead of having separate capacitors for each interface pair, the design combines the decoupling functionality for multiple interfaces into one shared component. This merging reduces the total number of components that need to be placed, wired, and tested during manufacturing, thereby reducing overall manufacturing cost while maintaining the necessary electrical performance for noise reduction.
3Area of stationary object
If a single decoupling capacitor is shared between multiple interfaces, then die area and cost are reduced, but the ability to provide dedicated noise isolation for each interface may be compromised
Solution Approach 1:
The patent segments the connection path between the shared capacitor and the interfaces using selective connection mechanisms such as bond wires or connection members. While the capacitor itself is shared, the connection paths to different interface pairs are separated and can be independently controlled. This segmentation allows the shared capacitor to provide dedicated noise isolation for the active interface pair by connecting only to those interfaces through selective wiring, while leaving other interface connections open or disconnected. This maintains the noise isolation capability equivalent to having separate capacitors for each interface pair.
Data Source
AI summary
A semiconductor device has an on-die decoupling capacitor that is shared between alternative high-speed interfaces. A capacitance pad is connected to the decoupling capacitor and internal connection pads are connected respectively to the alternative interfaces. Internal connection bond wires connect the decoupling capacitor to the selected interface through the capacitance pad and the internal connection pads in the same process as connecting the die to external electrical contacts of the device.