RF Inductor Coupling Circuit With Integrated Harmonic Filtering
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Solution Overview
Problem
Existing radio frequency (RF) circuits face challenges in efficiently filtering harmonics without affecting the fundamental frequency, which can interfere with other circuits operating at different frequency bands.
Innovation Solution
The proposed solution integrates a harmonic filter circuit within the RF apparatus, utilizing a signal coupling circuit with primary and secondary side inductors, an extraction circuit with a center tap, and a resonant circuit to filter harmonics by generating a signal with the same frequency as the harmonic but with inverse phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a filter is provided outside the radio frequency circuit to filter harmonics, then the harmonics' influence on the circuit is reduced, but the performance of the radio frequency circuit is affected, additional circuit placement space is occupied and additional costs are produced
Solution Approach 1:
The patent merges the harmonic filtering function with the existing inductor in the radio frequency circuit by adding a capacitor connected to the center tap of the inductor, forming a resonant circuit that filters harmonics without requiring separate external filter components
Solution Approach 2:
The inductor in the radio frequency circuit is given dual functionality: it continues to perform its original signal coupling function while simultaneously serving as part of a resonant circuit that filters harmonics, eliminating the need for dedicated external filter components
2Object-affected harmful factors
If a filter is provided outside the radio frequency circuit to filter harmonics, then the harmonics' influence on the circuit is reduced, but the occupied circuit (or chip) space increases
Solution Approach 1:
The filtering function is merged into the existing inductor structure by utilizing its center tap to connect a capacitor, forming a resonant circuit that occupies no additional chip space while effectively filtering harmonics
3Object-affected harmful factors
If a filter is provided outside the radio frequency circuit to filter harmonics, then the harmonics' influence on the circuit is reduced, but additional costs are produced
Solution Approach 1:
The existing inductor is made multi-functional by adding a capacitor to its center tap, enabling it to perform both signal coupling and harmonic filtering functions, thereby eliminating the need for separate external filter components and reducing overall manufacturing costs
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 approach effectively reduces harmonics in the output signal without affecting the fundamental frequency, thereby minimizing interference with other circuits and reducing the need for external filters, which can save space and costs.
Implementation Method 1
a resonant circuit to filter harmonics by generating a signal with the same frequency as the harmonic but with inverse phase
Implementation Method 2
The signal coupling circuit includes a primary side inductor and a secondary side inductor. The signal coupling circuit is configured to receive the to-be filtered signal through the primary side inductor and to output a single-ended signal from the secondary side inductor
Data Source
AI summary
A radio frequency apparatus includes a power amplifier circuit, a signal coupling circuit, an extraction circuit, and a harmonic filter circuit. The power amplifier circuit is configured to amplify a differential signal to output a to-be-filtered signal. The signal coupling circuit includes a primary side inductor and a secondary side inductor. The signal coupling circuit is configured to convert the to-be-filtered signal received by the primary side inductor into a single-ended signal outputted from the secondary side inductor. The extraction circuit has a center tap. The extraction circuit is configured to inductively couple to the primary side inductor and output a common mode signal from the center tap. The harmonic filter circuit is configured to perform a harmonic filtering on the single-ended signal according to the common mode signal, such that the secondary side inductor of the signal coupling circuit outputs a filtered signal.