Multi-Band Filter Circuit Using Phase Adjustment to Cut Insertion Loss
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Solution Overview
Problem
In communication devices supporting multiple frequency bands, signal leakage between filters increases insertion loss, making it difficult to suppress leakage and reduce insertion loss effectively as the number of paths connected to a common point grows.
Innovation Solution
A filter circuit with a phase adjustment circuit that inverts the phase of signals in one frequency band, preventing leakage to another frequency band by making the impedance in the first frequency band appear open, thereby reducing insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple filters are connected to a common point to support multiple frequency bands, then the communication device can transmit and receive signals in multiple bands, but signal leakage occurs between paths causing insertion loss to increase
Solution Approach 1:
A phase adjustment circuit is introduced as an intermediary component between the common point and the second filter. This circuit adjusts the phase of signals in the first frequency band before they reach the second filter, preventing signal leakage from the first path to the second path. The phase adjustment circuit acts as a mediator that resolves the interference between multiple frequency bands while maintaining multi-band functionality.
Solution Approach 2:
The phase adjustment circuit changes the phase parameter of signals in the first frequency band. By adjusting the phase to specific values (such as 0 degrees or 180 degrees), the circuit creates constructive or destructive interference patterns that prevent signal leakage into the second path. This parameter change approach allows the system to maintain multi-band support while reducing insertion loss through controlled phase relationships.
2Loss of energy
If matching circuits are added to adjust impedance and suppress signal leakage, then signal leakage between filters can be reduced, but the impedance adjustment becomes difficult when a larger number of paths are connected
Solution Approach 1:
The phase adjustment circuit serves as a specialized intermediary that simplifies the impedance adjustment problem. Instead of requiring complex matching circuits for each path, the phase adjustment circuit provides a unified approach by controlling the phase relationship between paths. This reduces the overall complexity of impedance management in multi-path systems.
Solution Approach 2:
The invention changes the approach from adjusting impedance parameters to adjusting phase parameters. Phase adjustment is generally simpler and more controllable than impedance matching, especially in multi-path configurations. By focusing on phase parameter control, the system achieves effective signal leakage suppression without the complexity of multiple impedance matching circuits.
3Loss of energy
If phase adjustment circuit is introduced to reduce insertion loss, then signal leakage is suppressed effectively, but the device complexity increases
Solution Approach 1:
The phase adjustment circuit is positioned as a strategic intermediary at a critical point in the signal path. This placement allows it to control signals for multiple filters simultaneously, achieving effective leakage suppression with a single circuit rather than requiring multiple separate components for each filter pair.
Solution Approach 2:
The phase adjustment circuit performs multiple functions: it adjusts phase for signal leakage suppression, indirectly manages impedance relationships, and works across multiple frequency bands. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby limiting the overall increase in device complexity while achieving effective insertion loss reduction.
Data Source
AI summary
A filter circuit includes a filter that is disposed on a path connecting a common terminal and an input output terminal and uses a first frequency band as a pass band, a filter that is disposed on a path connecting the common terminal and an input output terminal and uses a second frequency band different from the first frequency band as a pass band, and a phase adjustment circuit that has an input terminal connected to the path and an output terminal connected to the path, and adjusts a phase of a signal in the first frequency band input from the path and outputs a signal having a phase different from a phase of the signal in the first frequency band to the output terminal, wherein the path and the path are paths through which a received signal passes.