RF Semiconductor Impedance Matching Circuit Layout
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Solution Overview
Problem
Designing packaged RF semiconductor devices for wideband, multi-band, and multi-mode operations is challenging due to limitations in lead level output impedance, inductive coupling between matching sections, and the need for large discrete capacitors, which increases package size, contradicting industry trends of reducing device size and cost.
Innovation Solution
The implementation of semiconductor devices using air cavity and overmolded packages with impedance matching elements positioned outside the active device area, reducing inductive coupling and allowing for smaller package sizes while maintaining desired electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple in-package matching sections are incorporated to achieve acceptable lead level output impedance for wideband operation, then the output impedance performance is improved, but the device size increases due to more impedance matching elements
Solution Approach 1:
The patent positions impedance matching elements outside the active device area, utilizing the package substrate area rather than confining all elements within the active device footprint. This dimensional repositioning allows multiple matching sections to be accommodated without proportionally increasing the active device area, resolving the contradiction between improved impedance performance and device size.
2Reliability
If multiple sets of bondwires are implemented to interconnect impedance matching elements for multi-stage matching, then the impedance transformation capability is improved, but inductive coupling between matching sections increases which limits effectiveness
Solution Approach 1:
The patent extracts the impedance matching elements from the congested active device area and positions them outside, reducing the inductive coupling between matching sections that occurs when multiple bondwire sets are densely packed. This separation maintains the impedance transformation capability while eliminating the harmful inductive coupling effect.
3Reliability
If relatively large discrete capacitors are used to facilitate good performance for wideband operation, then the electrical performance is improved, but the package size must be increased to accommodate them
Solution Approach 1:
The patent relocates large discrete capacitors outside the active device area onto the package substrate, allowing them to be positioned in available space without constraining the active device footprint. This enables the use of larger capacitors for improved wideband electrical performance without proportionally increasing the overall package size.
Data Source
AI summary
Embodiments of semiconductor devices (e.g., RF devices) include a substrate, an isolation structure, an active device, a lead, and a circuit. The isolation structure is coupled to the substrate, and includes an opening. An active device area is defined by a portion of the substrate surface that is exposed through the opening. The active device is coupled to the substrate surface within the active device area. The circuit is electrically coupled between the active device and the lead. The circuit includes one or more elements positioned outside the active device area (e.g., physically coupled to the isolation structure and/or under the lead). The elements positioned outside the active device area may include elements of an envelope termination circuit and/or an impedance matching circuit. Embodiments also include method of manufacturing such semiconductor devices.