Harmonic Phase Tuning Filter for RF Switch
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Solution Overview
Problem
Conventional multi-throw RF switches in mobile communication devices, such as those using the GSM standard, face challenges in reducing harmonics like third harmonics generated by power amplifiers, as existing filters do not provide sufficient reduction.
Innovation Solution
Integration of a harmonic phase tuning filter with the RF switch, which tunes the phase of harmonics to provide a selected impedance, either high (phase open) or low (phase short), to effectively reduce harmonic levels while matching the output impedance to the fundamental frequency, thereby improving harmonic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conventional filter is coupled between the input of the RF switch and the power amplifier, then the level of harmonics generated by the power amplifier is reduced, but the filter does not provide sufficient reduction in harmonics generated by the RF switch itself
Solution Approach 1:
The filter is divided into multiple independent tuning circuits, each targeting specific harmonic frequencies. This segmentation allows the filter to address different harmonic sources (power amplifier harmonics and switch-generated harmonics) separately, achieving comprehensive harmonic reduction where a single conventional filter failed.
Solution Approach 2:
The patent employs variable capacitors and inductors that can be dynamically adjusted to change the filter's impedance characteristics at different harmonic frequencies. By tuning these parameters, the filter adapts to reduce both power amplifier harmonics and switch-generated harmonics effectively, resolving the insufficiency of fixed conventional filters.
2Object-generated harmful factors
If a filter is added to reduce harmonics, then harmonic performance improves, but the device complexity increases
Solution Approach 1:
The filter design merges multiple tuning circuits into a single integrated structure that handles multiple harmonic frequencies simultaneously. By combining several LC circuits with variable elements into one unified filter module, the patent reduces device complexity compared to using multiple separate filters, while maintaining effective harmonic reduction performance.
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 harmonic phase tuning filter significantly reduces third harmonic levels and maintains a desired output impedance at the fundamental frequency, enhancing the overall harmonic performance of the RF switch.
Implementation Method 1
a harmonic phase tuning filter coupled to an input of an RF switch, and configured to provide a selected impedance at a harmonic frequency, such as a third harmonic frequency, generated by the RF switch by appropriately tuning the phase of the harmonic
Implementation Method 2
The selected impedance can be provided by appropriately rotating the phase of the harmonic frequency between a phase open and a phase short. The harmonic phase tuning filter can also be configured to provide an output impedance that substantially matches an input impedance of the RF switch at a fundamental frequency
Data Source
AI summary
According to one exemplary embodiment, a switching module includes a first harmonic phase tuning filter coupled to a first input of an RF switch. The first harmonic phase tuning filter is configured to provide an output impedance that substantially matches an input impedance of the RF switch at approximately a fundamental frequency and to provide a high impedance at approximately a harmonic frequency generated by the RF switch. The first harmonic phase tuning filter includes an LC circuit coupled between input and output terminals of the first harmonic phase tuning filter and tuned to provide the high impedance at approximately the harmonic frequency generated by the RF switch. The RF switching module further includes a second harmonic phase tuning filter coupled to a second input of the RF switch. The first and second harmonic phase tuning filters can be fabricated on a single semiconductor die.