RF Switch Segmentation for IM3 Cancellation
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Solution Overview
Problem
Current mobile terminal technologies face significant interference issues due to the generation of third-order intermodulation (IM3) products in nonlinear electronic components, which hinder simultaneous voice and LTE (SV-LTE) operation by de-sensing receivers, as these products fall within the pass bands of the receivers and are difficult to attenuate with simple filters.
Innovation Solution
The implementation of an RF switch with N semiconductor switch segments and N-1 phase shift networks, where individual phase shift networks are coupled between adjacent semiconductor switch segments, effectively phase shifts IM3 products, allowing for their partial cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two cellular front ends operate simultaneously for SV-LTE, then simultaneous voice and LTE operation is enabled, but third-order intermodulation products are generated that de-sense receivers
Solution Approach 1:
The RF switch is divided into N semiconductor switch segments with N-1 phase shift networks inserted between adjacent segments. This segmentation allows different portions of the signal path to introduce different phase shifts, enabling IM3 product cancellation while maintaining simultaneous voice and LTE operation.
Solution Approach 2:
The invention converts the harmful IM3 products generated by nonlinear components into beneficial cancelling signals by introducing phase shift networks that create out-of-phase versions of these products. The phase-shifted IM3 products interfere destructively with the original IM3 products, converting the harmful interference into a cancellation mechanism.
2Object-affected harmful factors
If phase shift networks are added to cancel IM3 products, then IM3 suppression is achieved, but device complexity increases
Solution Approach 1:
The phase shift networks modify the phase parameter of signals passing through different segments of the RF switch. By carefully controlling the phase shift values (e.g., 180 degrees for IM3 products), the system achieves cancellation of harmful IM3 products while maintaining the desired signal integrity. This parameter-based approach provides a systematic way to manage complexity.
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
This solution significantly reduces IM3 products, providing at least 11 dB of suppression even under worst-case antenna VSWR conditions, thereby enhancing the operational capability of mobile terminals to handle simultaneous voice and LTE signals without de-sensing receivers.
Implementation Method 1
individual ones of the N−1 phase shift networks are coupled between adjacent ones of the N semiconductor switch segments where N is a natural number greater than 1. In operation, when the RF switch is on, IM3 products generated by the RF switch propagating through the N−1 phase shift networks are phase shifted such that the IM3 products are at least partially canceled.
Implementation Method 2
IM3 products generated by the RF switch propagating through the N−1 phase shift networks are phase shifted such that the IM3 products are at least partially canceled
Data Source
AI summary
A radio frequency (RF) switch adapted to reduce third order intermodulation (IM3) products generated as RF signals propagate through the RF switch is disclosed. The RF switch includes N semiconductor switch segments, and N−1 phase shift networks, individual ones of the N−1 phase shift networks being coupled between adjacent ones of the N semiconductor switch segments where N is a natural number greater than 1. In operation, when the RF switch is on, IM3 products generated by the RF switch propagating through the N−1 phase shift networks are phase shifted such that the IM3 products are at least partially canceled.