Deep-well noise shield for inductor density and jitter
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Solution Overview
Problem
In high-performance integrated circuits, magnetic and substrate coupling limits jitter performance and density of inductive components due to noise coupling between inductors and the substrate.
Innovation Solution
A shielded inductor design featuring conductive loops on a deep-well noise shield with a peripheral well, deep-well layer, and slot wells that provide p-n junctions to isolate noise coupling, subdividing the well into separate areas to reduce noise interference and maintain inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inductors are closely-spaced in integrated circuits, then density is improved, but magnetic and substrate coupling increases causing jitter performance degradation
Solution Approach 1:
The inductor structure is segmented into multiple conductive loops that are electrically connected, creating a distributed inductive element. This segmentation allows for better noise isolation while maintaining total inductance, enabling closer spacing without degrading jitter performance.
Solution Approach 2:
A deep-well noise shield is introduced as an intermediary structure between the conductive loops and the substrate. This noise shield, formed by a deep well extending into the substrate, acts as a mediator to block substrate noise coupling and magnetic interference, allowing inductors to be placed closer together without compromising jitter performance.
2Object-affected harmful factors
If conventional shielding structures are used, then noise coupling is reduced, but inductor density and area utilization deteriorate
Solution Approach 1:
The noise shield deep well is nested within the inductor structure itself, with the well extending downward into the substrate beneath the conductive loops. This nested configuration provides effective noise shielding without requiring additional lateral space, maintaining high area utilization while reducing noise coupling.
Solution Approach 2:
The shielding approach transitions from lateral/planar shielding to vertical depth-based shielding. By extending the noise shield deep into the substrate vertically rather than expanding laterally, the structure achieves effective noise isolation while maintaining compact footprint and high density.
3Object-affected harmful factors
If deep-well noise shield is implemented, then substrate noise coupling is isolated, but device complexity increases
Solution Approach 1:
The deep-well noise shield serves multiple functions simultaneously: it acts as a noise isolation barrier, provides magnetic shielding, and can be integrated with the inductor fabrication process. This multi-functionality reduces the need for separate shielding structures, simplifying the overall device architecture despite the deep well implementation.
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 solution effectively isolates noise coupling, allowing for closer packing of inductors and improved jitter performance by diverting noise to the power network, while maintaining inductance and reducing substrate noise interference.
Implementation Method 1
The peripheral well and the deep-well layer are coupled together to provide two p-n junctions that separate the first well and the substrate
Data Source
AI summary
A shielded inductor in an integrated circuit includes conductive loops disposed on a deep-well noise shield for isolating a noise coupling between the conductive loops and the substrate of the integrated circuit. The deep-well noise shield includes a first well disposed within a second well that is disposed within the substrate of the integrated circuit. The second well includes a peripheral well, a deep-well layer, and slot wells. The peripheral well surrounds a periphery of the first well. The peripheral well and the deep-well layer are coupled together to provide two p-n junctions that separate the first well and the substrate. The slot wells are distributed inside the periphery of the first well. Each slot well and the deep-well layer are coupled together. Each slot well has a width and a length that is at least three times the width.