Coplane low-pass filter

Abstract

The invention relates to a coplane low-pass filter which comprises a substrate, a center conductor, two grounding surfaces, a first coupling line, two second coupling lines and four third coupling lines. The substrate has a first surface, wherein the surface is provided with a signal input port and a signal output port which are separated oppositely; the center conductor comprises a first end in electrical connection with the signal input port, a second end in electrical connection with the signal output port, and a center portion; each grounding surface is provided with a groove in the place corresponding to the center portion of the center conductor; the first coupling line has two open circuit ends, wherein the two open circuit ends extend into the grooves in the two grounding surfaces respectively; a gap is formed between each second coupling line and the center conductor; the four third coupling lines each have a feed-in end and an open circuit end, wherein a gap is formed between the open circuit end of each third coupling line and first coupling line, and attenuation characteristics and 3-dB cut-off frequency of the coplane low-pass filter can be adjusted by changing the distance of the gap as well as the first distance and the second distance. Through the structure above, the coplane low-pass filter has the beneficial effects of simple structure, low insertion loss and high attenuation rate and the like.

Description

Technical field [0001] The invention relates to a filter, in particular to a coplanar low-pass filter. Background technique [0002] At present, since the chip size is limited by passive components rather than active components, it has become a trend to develop miniaturized coplanar waveguide (CPW) passive devices to shrink microwave monolithic integrated circuits (MMICs). However, the operating frequency of integrated high-resistance silicon substrates and applied to centimeter-wave passive components is greatly limited. [0003] Coplanar Waveguide (CPW) transmission line can be measured on a high-resistance silicon substrate with a resistivity (ρ) of 2500Ω-cm at 30GHz to be 0.1 dB / mm, showing that passive devices can be applied to a high-resistance silicon substrate Centimeter wave operation. In the prior art, proton implantation is used to implement an integrated coplanar waveguide coplanar low pass filter on a high resistance silicon substrate with a resistivity (ρ) of 100 kΩ...

AI Technical Summary

Problems solved by technology

However, the coplanar waveguide (CPW) coplanar low-pass filter formed by the proton implantation method still needs to be improved in terms of insertion loss and attenuation rate.

Images