Integrated Duplexer Receive Filter with Matched Balun
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Solution Overview
Problem
Conventional duplexer designs for portable communication devices require multiple LC components for balun and impedance matching, increasing size, cost, and insertion loss due to the need for phase matching inductors in both the receive filter and balun.
Innovation Solution
A duplexer with an integrated receive filter and a matched balun that replaces the phase matching inductor, using a configuration with capacitors and inductors to provide differential output signals without the need for additional phase matching inductors, reducing the number of LC elements and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional matched balun design with separate phase matching inductors is used, then impedance matching and signal conversion are achieved, but the number of LC components increases, leading to larger size, higher cost, and increased insertion loss
Solution Approach 1:
The patent combines the phase matching inductor and the balun inductor into a single shared inductor component. This merging eliminates redundant components while maintaining both the impedance matching function and the single-ended to differential signal conversion function, thereby reducing the total number of LC elements without compromising performance
Solution Approach 2:
The shared inductor serves multiple functions simultaneously: it acts as both the phase matching inductor for impedance matching and as one of the inductors in the balun circuit for signal conversion. This multi-functionality reduces component count and simplifies the overall circuit architecture
2Manufacturing precision
If multiple phase matching inductors are used in receive filter and balun, then proper phase matching is achieved, but physical size and fabrication complexity increase
Solution Approach 1:
By merging the phase matching inductor and balun inductor into a single component, the patent reduces the number of fabrication steps required. Fewer discrete components mean fewer assembly operations, soldering steps, and alignment procedures, thereby improving ease of manufacture while maintaining phase matching accuracy through proper design of the shared inductor
3Ease of operation
If conventional balun circuit with multiple inductors and capacitors is used, then signal conversion from single-ended to differential is achieved, but insertion loss increases
Solution Approach 1:
The patent extracts and eliminates redundant inductor components from the conventional balun circuit. By removing unnecessary inductors and using a shared inductor approach, the total parasitic resistance is reduced, which directly lowers insertion loss while maintaining the essential signal conversion function from single-ended to differential signals
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 design reduces the physical size and complexity of the duplexer, lowers cost, and minimizes insertion loss, enabling a smaller form factor and improved performance by eliminating unnecessary inductors and matching circuits.
Implementation Method 1
a receive filter portion having multiple acoustic resonator filter elements
Implementation Method 2
A matched balun is integrated into the duplexer, replacing the phase matching inductor of the receive filter and balun
Data Source
AI summary
A duplexer includes a transmit filter and an integrated receive filter configured to filter a receive signal from an antenna. The integrated receive filter includes a receive filter portion having multiple acoustic resonator filter elements and a matched balun configured to convert a single-ended input signal, received at a single-ended input of the matched balun from a single-ended output of the receive filter portion, to a differential output signal. The matched balun being is located in place of a phase matching inductor of the receive filter portion, eliminating need for the phase matching inductor of the receive filter portion and a phase matching inductor of the matched balun. Impedance at the single-ended input of the matched balun includes a complex conjugate of impedance at the single-ended output of the receive filter portion.