Adjustable Impedance Matching Network Using Non-Directional Coupler
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Solution Overview
Problem
Impedance mismatch between power amplifiers and antennas in wireless communications devices leads to reduced radiated power and efficiency, requiring over-design of power amplifiers and the use of directional couplers with limited dynamic range and increased complexity for wide frequency bands.
Innovation Solution
A mobile wireless communications device employs a non-directional coupler and an adjustable impedance matching network controlled by a feedback system using a controller and LMS algorithm, eliminating the need for directional couplers and enabling operation over a wide frequency band with reduced complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a directional coupler is used to measure forward and reflected power for impedance matching, then the impedance matching can be adjusted, but the dynamic range and directivity are limited over a wide frequency band
Solution Approach 1:
The patent uses a single non-directional coupler that can operate across a wide frequency band (e.g., 700 MHz to 3.8 GHz) to perform both forward and reflected power measurements. This single component serves multiple frequency bands that would traditionally require multiple directional couplers, achieving universality across frequency ranges.
Solution Approach 2:
Instead of using a directional coupler that physically separates forward and reflected waves through directional elements, the patent inverts the approach by using a non-directional coupler with a directional bridge circuit that electronically determines wave direction based on signal phase relationships. This allows the same hardware to function directionally without requiring physical directional coupling structures.
2Adaptability or versatility
If multiple directional couplers are used to support a wide frequency band, then the frequency band coverage is improved, but the cost and complexity of the device increases
Solution Approach 1:
A single non-directional coupler is designed to handle multiple frequency bands (e.g., GSM 850, GSM 900, DCS 1800, PCS 1900, and AWS 2100 bands) that would traditionally require separate directional couplers for each band. This universal component reduces the total number of parts needed in the system.
Solution Approach 2:
The patent combines the functions of multiple directional couplers into a single non-directional coupler paired with a directional bridge circuit. This merging consolidates what would be separate measurement paths into one integrated system, reducing component count and interconnections.
Solution Approach 3:
The directional bridge circuit acts as an intermediary that processes the outputs from the non-directional coupler to determine forward and reflected power. This mediator component enables a single non-directional coupler to perform the function of multiple directional couplers through signal processing rather than physical separation.
3Power
If the power amplifier is over-designed to provide sufficient output power under poor impedance matching conditions, then the radiated power specification can be met, but the efficiency of the power amplifier is lowered
Solution Approach 1:
The patent implements a feedback system that continuously measures forward and reflected power using the non-directional coupler and directional bridge circuit. The reflected power information is fed back to the controller, which adjusts the impedance matching network in real-time to minimize reflections and maximize power transfer to the antenna, preventing the need for over-designing the power amplifier.
Solution Approach 2:
The impedance matching network uses variable capacitors (such as BST or MEM capacitors) that can be dynamically adjusted under applied control voltage to change capacitance values. This dynamic adjustment allows the system to adapt to changing impedance conditions and maintain optimal power transfer efficiency across different operating conditions.
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 solution effectively adjusts impedance matching to maximize radiated power and efficiency across multiple frequency bands, reducing the need for multiple directional couplers and lowering device complexity and cost while maintaining performance over temperature and frequency changes.
Implementation Method 1
the non-directional coupler comprises a signal path conductor and a feedback path conductor inductively coupled thereto
Data Source
AI summary
A mobile wireless communications device includes a portable housing, a transmitter carried by the portable housing and configured to modulate an input signal, and an adjustable impedance matching network coupled downstream from the transmitter. An antenna is coupled downstream from the adjustable impedance matching network, and a non-directional coupler is coupled between the adjustable impedance matching network and the antenna. A feedback receiver is coupled to the non-directional coupler to generate a feedback signal. A controller is configured to control the adjustable impedance matching network based upon the input signal and the feedback signal.