RF Differential Signal Trace Layout for Harmonic Interference
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Solution Overview
Problem
Conventional trace layouts for multiphase signals in RF receivers generate significant radiation interference, particularly at high local oscillator frequencies and their harmonics.
Innovation Solution
A layout of signal traces with specific configurations, including parallel and non-straight line segments, differential signal transmission, and interlayer coupling via vias, to minimize radiation interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional trace layout is used for transmitting multiphase signals, then signal transmission is achieved, but radiation interference is generated which interferes with peripheral circuits
Solution Approach 1:
The trace layout is divided into multiple segments with different orientations. Each segment transmits signals in a specific direction, and by segmenting the overall trace path into orthogonally oriented segments, the radiation interference is divided and directed in different directions, reducing cumulative interference in any single direction.
Solution Approach 2:
The patent employs asymmetric trace routing where traces for different phases are intentionally routed with different lengths and orientations. Specifically, traces are designed with orthogonal segments rather than symmetric parallel paths, creating asymmetric current distribution that reduces common-mode radiation while maintaining differential signal integrity.
2Speed
If high LO frequency oscillation signals are used, then signal processing capability is improved, but harmonic frequency interference is intensified
Solution Approach 1:
The patent transitions from planar trace routing to three-dimensional routing by utilizing multiple PCB layers. Traces are distributed across different layers with orthogonal orientations, effectively adding a vertical dimension to the trace layout. This spatial distribution reduces the concentration of harmonic radiation in any single plane, mitigating interference while maintaining high-frequency signal processing capability.
Data Source
AI summary
A layout of signal traces includes a first set of signal traces and a second set of signal traces that are used for transmitting a first differential signal and a second differential signal respectively. Each set of signal traces includes a first part, a second part, and a third part along the direction of signal transmission. Different parts of the same signal trace as a whole is not straight. All the first parts are in a first signal layer and parallel. The second parts of the two sets of signal traces are in a second signal layer and the first signal layer, respectively, and are across each other. The second part of the first/second set of signal traces is coupled with the first and third parts of the first/second set of signal traces. All the third parts are in the first signal layer and parallel.