Balanced Filter with IPD Balun for Insertion Loss Reduction
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Solution Overview
Problem
Existing balanced filters and duplexers with lumped parameter baluns suffer from high insertion loss and poor balance characteristics due to low Q values of inductors and capacitors, leading to inadequate performance in high-frequency applications.
Innovation Solution
A balanced filter and duplexer design incorporating a lumped parameter balun formed with integrated passive devices (IPDs) and a mounting unit for flip-chip assembly, utilizing IPD inductors and capacitors with high Q values, and a ground inductor connected between a node and the ground, to improve phase and amplitude balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a lumped parameter balun with conventional inductors and capacitors is used, then the device complexity is reduced, but the insertion loss increases and balance characteristics deteriorate due to low Q values
Solution Approach 1:
The patent changes the Q value parameter of the inductors and capacitors by selecting high-Q components (Q≥10 at 2 GHz for inductors, Q≥20 for capacitors). This parameter change directly reduces insertion loss while maintaining the lumped parameter balun structure, resolving the contradiction between simplicity and performance.
2Device complexity
If a lumped parameter balun with conventional inductors and capacitors is used, then the device complexity is reduced, but the amplitude balance and phase balance deteriorate
Solution Approach 1:
The patent improves balance characteristics by changing the Q value parameter of the components to be sufficiently high (Q≥10 for inductors, Q≥20 for capacitors). This ensures that the amplitude balance remains within ±0.5 dB and phase balance within ±5 degrees at the center frequency, resolving the contradiction between structural simplicity and balance precision.
3Loss of energy
If high Q-value inductors and capacitors are used in the lumped parameter balun, then the insertion loss is reduced, but the cost and manufacturing difficulty increase
Solution Approach 1:
The patent specifies minimum Q value thresholds (Q≥10 at 2 GHz for inductors, Q≥20 for capacitors) rather than requiring extremely high values. This pragmatic parameter selection achieves sufficient performance improvement while maintaining reasonable manufacturability, avoiding the need for specialized or expensive components.
Data Source
AI summary
A balanced filter includes: a filter that has at least one unbalanced signal terminal; a balun that is a lumped parameter balun that inputs or outputs signals with different phases generated based on a signal input or output from the unbalanced signal terminal of the filter, the balun being formed with an integrated passive device; and a mounting unit in which the filter and the balun are flip-chip mounted.