Capless Impedance Tuner Using Switchable Inductance Paths
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Solution Overview
Problem
In RF applications, power transfer efficiency is degraded due to impedance mismatches between radio circuits and antennas, as existing impedance tuners often rely on capacitors that introduce insertion loss and require numerous switches, complicating fine-tuning while increasing switch loss.
Innovation Solution
A capless impedance tuner with switchable series and shunt paths, including inductance paths, that allows for impedance matching without discrete capacitors or metal-insulator-metal capacitors, using parasitic capacitance and inductance properties of metal traces to provide tunable impedance transformation between nodes, minimizing insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional impedance tuners use discrete capacitors and multiple switches, then impedance tuning capability is improved, but insertion loss increases and device complexity increases
Solution Approach 1:
The patent removes discrete capacitors from the impedance tuning circuit, extracting the harmful capacitive elements that cause insertion loss. Instead, it uses only inductance paths with switches, eliminating the source of significant energy loss while maintaining impedance tuning functionality through controlled inductance variations.
Solution Approach 2:
The patent substitutes the traditional capacitor-based tuning mechanism with an inductance-based mechanism. By replacing capacitive elements with inductive elements and using switch-controlled inductance paths, the system achieves impedance tuning without the losses associated with capacitors and their associated switching networks.
2Measurement precision
If traditional impedance tuners use multiple switches for fine-tuning, then impedance matching precision is improved, but switch loss increases
Solution Approach 1:
The patent extracts and removes the excessive number of switches from the tuning circuit. By using fewer switch elements controlling inductance paths rather than multiple switches for capacitor selection, it reduces switch loss while achieving sufficient impedance matching precision through the inductance-based tuning mechanism.
3Adaptability or versatility
If traditional impedance tuners use discrete capacitors, then impedance tuning range is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates discrete capacitors from the circuit, significantly reducing component count and circuit complexity. The impedance tuning range is maintained through switchable inductance paths, which require fewer components and simpler circuit topology compared to traditional capacitor-based tuning networks.
Solution Approach 2:
The patent uses metal traces with inherent parasitic inductance and capacitance properties as composite tuning elements. By utilizing the natural electrical characteristics of the PCB or substrate traces rather than discrete components, it achieves impedance tuning functionality with reduced complexity and fewer discrete parts.
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 capless impedance tuner effectively matches antenna impedance to the radio circuit's source impedance, maximizing power transfer with reduced insertion loss and fine-tuning capabilities, particularly suitable for high-frequency bands like 5 GHz WLAN, by utilizing equivalent LC circuits and switchable paths to achieve desired impedance states.
Implementation Method 1
using parasitic capacitance and inductance properties of metal traces to provide tunable impedance transformation between nodes
Implementation Method 2
using parasitic capacitance and inductance properties of metal traces to provide tunable impedance transformation between nodes
Implementation Method 3
a switchable grounding path implemented along the inductance path and configured to allow the inductance path to function as a series inductance path between the first and second nodes, or as a shunt inductance path between the ground and a node along the inductance path
Data Source
AI summary
Circuits, devices and methods related to impedance tuners. In some embodiments, a capless impedance tuner can include first node and second nodes, a first series path, a second series path, and an inductance path, each between the first node and the second node and including a switch to allow the path to couple or uncouple the first and second nodes. Each series path can be configured to allow a substantially continuous flow of a direct current between the first node and the second node when coupled. The tuner can further include a shunt path with a switch to allow coupling or uncoupling of the second node and ground. The tuner can further include a switchable grounding path implemented along the inductance path and configured to allow the inductance path to function as a series inductance path between the first and second nodes, or as a shunt inductance path between the ground and a node along the inductance path.