Reference Voltage Layer Impedance Calibrator for Easier Routing
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Solution Overview
Problem
As semiconductor devices become more integrated, forming impedance calibrators in conductive layers becomes challenging due to the increasing complexity of conductive interconnections.
Innovation Solution
The impedance calibrator is integrated into a reference voltage layer instead of the signal transmission layer, with structures like spiral, plate, and web shapes, and bridges connecting to the reference voltage layer, allowing for easier formation and improved signal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the impedance calibrator is formed in the signal transmission layer, then it can directly adjust signal impedance, but the conductive interconnections become increasingly complex and difficult to form as device integration increases
Solution Approach 1:
The impedance calibrator is relocated from the signal transmission layer to the reference voltage layer, utilizing the vertical dimension of multi-layer PCB architecture. This spatial relocation allows the calibrator to be formed in a layer with simpler conductive patterns, avoiding the complexity of signal transmission interconnections while maintaining impedance calibration functionality through coupling mechanisms.
Solution Approach 2:
A coupling mechanism (such as a via hole or conductive bridge) is introduced as an intermediary element between the reference voltage layer containing the impedance calibrator and the signal transmission layer. This intermediary enables the impedance calibrator to indirectly adjust signal impedance by coupling with the signal transmission path, eliminating the need for direct formation of complex conductive interconnections in the signal layer.
2Ease of manufacture
If the impedance calibrator is placed in the reference voltage layer, then pattern density in the signal transmission layer is reduced and routing is facilitated, but additional coupling structures (bridges) are required to connect the calibrator to the reference voltage layer
Solution Approach 1:
The impedance calibrator structure is segmented into distinct components: the calibrator pattern itself in the reference voltage layer, coupling structures (via holes or bridges), and the signal transmission path. This segmentation allows each component to be optimized independently - the calibrator pattern can be simple in the reference layer while the coupling structures provide the necessary electrical connection, simplifying overall manufacturing.
Solution Approach 2:
The reference voltage layer serves multiple functions: it provides reference voltage, houses the impedance calibrator, and contains coupling structures to connect with signal transmission layers. This multi-functionality consolidates what would otherwise require separate structures, reducing overall device complexity while maintaining routing simplicity in the signal transmission layer.
3Manufacturing precision
If the impedance calibrator uses spiral, plate, or web shapes, then it achieves effective impedance calibration, but the formation process becomes more complex compared to simple patterns
Solution Approach 1:
The impedance calibrator utilizes patterns with specific geometric parameters (spiral, plate, or web shapes) that can be systematically varied to achieve desired calibration results. These parameter changes in pattern geometry allow effective impedance calibration while maintaining compatibility with standard PCB manufacturing processes, as the shapes can be formed using conventional photolithography and etching techniques.
Data Source
AI summary
A substrate in accordance with an embodiment of the disclosure includes a signal transmission layer including a signal transmission pad and a signal transmission interconnection; a first dielectric layer stacked on the signal transmission layer; and a first reference voltage layer stacked on the first dielectric layer. The first reference voltage layer includes a first space hole and an impedance calibrator. The impedance calibrator includes an impedance calibration part disposed in the first space hole; and a first bridge connecting a first portion of the impedance calibration part to a first portion of the first reference voltage layer.