Microstrip Filter With Capacitive Coupling For 5G mmWave
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Solution Overview
Problem
Existing SAW and BAW filters used in RFFE modules for high-frequency applications, such as 5G mmWave services, experience increased passband return loss and poor stopband attenuation, making them unsuitable for modern wireless communication requirements.
Innovation Solution
A filter design incorporating a dielectric substrate, ground layer, microstrip line layer, signal vias, and capacitive coupling units, which includes at least three microstrip resonators and a capacitive coupling unit capacitive-coupled with adjacent resonators, forming a stack of thin and thick layers to achieve improved performance in miniaturization and frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If SAW and BAW filters are used in high-frequency applications, then the filters can operate at high frequencies, but the passband return loss increases and stopband attenuation deteriorates
Solution Approach 1:
The patent replaces the acoustic wave mechanism (mechanical vibration) of SAW and BAW filters with an electromagnetic field-based microstrip resonator system. The microstrip resonators operate at high frequencies using electromagnetic resonance rather than acoustic wave propagation, eliminating the inherent limitations of acoustic wave filters at mmWave frequencies while maintaining reliable passband and stopband characteristics
Solution Approach 2:
The patent changes the fundamental operating parameter from acoustic wave frequency to electromagnetic resonance frequency. By designing microstrip resonators with specific electrical lengths and impedance values, the filter achieves optimal performance at high frequencies including 5G mmWave bands, where traditional acoustic wave filters fail to maintain proper return loss and attenuation characteristics
2Adaptability or versatility
If multiple filtering components are added to cover more frequency bands, then the communication mode coverage increases, but the device size increases
Solution Approach 1:
The microstrip resonator filter structure is designed to be multi-functional, capable of operating across multiple frequency bands including 2G, 3G, 4G, and 5G mmWave services. By adjusting the resonator dimensions and configuration, a single filter design can cover diverse frequency ranges, eliminating the need for separate filters for each band and significantly reducing the overall device area
Solution Approach 2:
The patent transitions from planar filter layouts to a three-dimensional stacked configuration with multiple layers. This vertical integration allows multiple filtering functions to be stacked in the Z-dimension rather than arranged side-by-side in the XY plane, effectively reducing the footprint area while maintaining multi-band coverage capabilities
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 filter achieves low passband insertion loss and high stopband suppression, making it more suitable for high-frequency applications and addressing the limitations of traditional SAW and BAW filters.
Implementation Method 1
The microstrip line layer is located on another surface of the dielectric substrate and includes at least three microstrip resonators... The filter achieves low passband insertion loss and high stopband suppression
Implementation Method 2
The filter further includes at least one capacitive coupling unit capacitive-coupled with two of the at least three microstrip resonators adjacent to each other
Implementation Method 3
a dielectric substrate, a ground layer... The ground layer is formed on a surface of the dielectric substrate
Data Source
AI summary
The disclosure relates to a filter including dielectric substrate, ground and microstrip line layers, and signal and ground vias. The ground layer is formed on the dielectric substrate and has a ground plane and signal terminal contacts. The microstrip line layer is located on the dielectric substrate and includes microstrip resonators, common electrode and input and output terminal contacts. The input and output terminal contacts are connected to the microstrip resonators. The signal and ground vias extend among the ground layer, the dielectric substrate, and the microstrip line layer. The signal terminal contacts are connected to the input and output terminal contacts through the signal vias. The ground plane is connected to the common electrode through the ground vias. The filter further includes at least one capacitive coupling unit capacitive-coupled with two of the microstrip resonators adjacent to each other.