Variable-Inductor Balun for Shared-Antenna RF Impedance Matching
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Solution Overview
Problem
Conventional RFICs without an impedance matching circuit dedicated to transmission face challenges in maintaining reception performance while minimizing signal loss during transmission operations.
Innovation Solution
A balun circuit with a first inductor coupled to a transmitter and a second inductor with mutual inductance, which is variable, is introduced between the transmitter and a common antenna terminal, allowing inductance value adjustment between transmission and reception operations to prevent reception performance deterioration and signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common antenna terminal is shared between transmitter and receiver without a dedicated impedance matching circuit for transmission, then device complexity is reduced, but signal loss during transmission increases and reception performance deteriorates
Solution Approach 1:
The patent employs a variable inductor whose inductance value can be dynamically changed between transmission and reception operations. During transmission, the inductor is adjusted to an optimal value for minimizing signal loss, while during reception, it is adjusted to maintain high reception performance. This dynamic adjustment resolves the contradiction by allowing the same circuit component to optimize for different operational modes without requiring separate dedicated circuits.
Solution Approach 2:
The patent changes the inductance parameter of the second inductor based on operational mode (transmission or reception). By controlling the inductance value to be different for transmission and reception, the system achieves optimal impedance matching for each mode using a single shared antenna terminal, thereby reducing signal loss during transmission while maintaining high reception performance without increasing device complexity.
2Loss of energy
If a variable inductor with mutual inductance is added to the balun circuit to enable inductance adjustment, then signal loss during transmission is reduced and reception performance is maintained, but device complexity increases
Solution Approach 1:
The variable inductor with mutual inductance serves multiple functions: it acts as part of the balun circuit for impedance transformation, provides impedance matching for both transmission and reception modes, and enables dynamic adaptation to different operational requirements. By making this single component multi-functional, the patent reduces signal loss and maintains reception performance without proportionally increasing device complexity.
3Loss of energy
If inductance values are dynamically adjusted between transmission and reception operations, then impedance matching efficiency is improved and signal loss is reduced, but control complexity increases
Solution Approach 1:
The patent implements a control circuit that automatically adjusts the inductance value of the variable inductor based on the operational mode (transmission or reception). This feedback mechanism ensures that the optimal inductance value is applied for each mode, achieving efficient impedance matching and reduced signal loss while automating the control process to minimize manual intervention and simplify operation.
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 enables efficient impedance matching, reducing signal loss during transmission and maintaining high reception performance by dynamically adjusting inductance values, thereby eliminating the need for an antenna switch and minimizing delay.
Implementation Method 1
the second inductor comprises an inductor having a mutual inductance with the first inductor
Data Source
AI summary
A balun circuit is disclosed. The balun circuit is provided between a transmitter and a common antenna terminal to which the transmitter and a receiver are coupled. The balun includes an inductor L1 coupled at one or both ends to the transmitter, an input node of the receiver, and an inductor L2 provided between ground or a first biasing power supply. The inductor L2 includes an inductor having a mutual inductance with the inductor L1. The inductor L2 is a variable inductor.