Microstrip DC Block Stepped Impedance Harmonic Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional microstrip DC blocks in high-frequency microwave circuits face issues with parasitic effects and harmonic interference, particularly in the 1 to 10 GHz range, due to the length of quarter-wave microstrip lines and the need for additional filtering structures.
Innovation Solution
A microstrip DC block design utilizing coupled stepped impedance lines and spur-lines, where the spur-lines are approximately λg/12 in length and the stepped impedance lines have a narrow and wide portion, effectively attenuating harmonic frequencies and reducing the overall length of the DC block, thereby minimizing interference and component size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If quarter-wave microstrip lines are used to create a DC block, then DC separation is achieved, but the length becomes too long (5mm to 50mm) and additional filtering structures are required
Solution Approach 1:
The DC block is segmented into multiple functional sections: a first microstrip line for DC blocking, a second microstrip line with different impedance characteristics, and a junction connecting them. This segmentation allows each section to be optimized for specific functions, achieving effective DC separation while reducing overall length and eliminating the need for additional filtering structures.
Solution Approach 2:
The invention changes the impedance parameter along the microstrip lines by introducing a second microstrip line with different characteristic impedance than the first line. This parameter variation creates the necessary electrical length equivalence to a quarter-wave line while using physically shorter structures, thereby reducing the DC block length while maintaining effectiveness.
2Reliability
If capacitors are used to create DC separation, then DC blocking is achieved, but parasitic effects and harmonic frequency transmission occur
Solution Approach 1:
The invention replaces the capacitor-based electrical component with a distributed microstrip line structure. This substitution eliminates the parasitic effects inherent in capacitors while maintaining the DC blocking function through the physical break and impedance discontinuity in the transmission line, thereby reducing harmful parasitic effects and harmonic interference.
3Object-generated harmful factors
If additional filtering structures are added to mitigate harmonic effects, then harmonic suppression is improved, but device complexity and cost increase
Solution Approach 1:
The second microstrip line serves multiple functions simultaneously: it provides DC blocking assistance, creates impedance transformation, and suppresses harmonic frequencies through its specific impedance characteristics. This multi-functionality eliminates the need for separate filtering structures, reducing device complexity while maintaining effective harmonic suppression.
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 proposed design significantly suppresses harmonic frequencies, reduces the footprint of the DC block by up to 30% compared to conventional quarter-wave microstrip DC blocks, and maintains effective transmission of the main signal frequency, thereby enhancing the operational integrity of RF circuits.
Implementation Method 1
a first stepped impedance line extending from the first signal line end towards the second signal line end, wherein the first stepped impedance line is parallel to the first spur-line
Implementation Method 2
a microstrip DC block comprising: a first signal line having a first signal line end; a second signal line having a second signal line end
Data Source
Figure 1~2
Figure 3
AI summary
A microstrip DC block (200) comprising: a first signal line (202) having a first signal line end (204) and a first centreline (C1); a second signal line (220) having a second signal line end (222) and a second centreline (C2); a first spur-line (206) extending from the first signal line end towards the second signal line end; a first stepped impedance line (208) extending from the first signal line end towards the second signal line end, wherein the first stepped impedance line is parallel to the first spur line; a second spur-line (224) extending from the second signal line end towards the first signal line end; a second stepped impedance line (226) extending from the second signal line end towards the first signal line end, wherein the second stepped impedance line is parallel to the second spur line, and wherein the second stepped impedance line is coupled to the first stepped impedance line.