A multilayer substrate, being divided into an input side region, an intermediate region, and an output side region in this order in a plan view, and the multilayer substrate comprising:
- a plurality of dielectric layers;
- a plurality of ground layers, provided on both surfaces of each of the plurality of dielectric layers, and the plurality of dielectric layers being stacked on each other via the ground layers;
- a signal line, provided on a surface of one of the plurality of dielectric layers that is provided at a top side of the plurality of dielectric layers, and the signal line extending from the input side region through the intermediate region to the output side region;
- and
- a plurality of vias, electrically connecting the plurality of ground layers by passing through at least one of the plurality of dielectric layers in a stacking direction of the plurality of dielectric layers, wherein
- the plurality of ground layers comprises:
- a plurality of input side ground layers, provided in the input side region where the signal line through which a signal is input,
- a plurality of output side ground layers, provided in the output side region where the signal line through which the signal is output, and
- a plurality of intermediate ground layers, provided in the intermediate region, and the intermediate ground layers being disposed between the input side ground layers and the output side ground layers, and
- the input side ground layers provided in the input side region have fewer layers than the intermediate ground layer provided in the intermediate region, and
- the output side ground layers provided in the output side region have fewer layers than the intermediate ground layer provided in the intermediate region;
- wherein the plurality of vias have a plurality of first vias, a plurality of second vias, a plurality of third vias and a plurality of fourth vias provided in the intermediate ground layer,
- the plurality of first vias is arranged in a direction parallel to the signal line on one side of the signal line in a width direction,
- the plurality of second vias is arranged in a direction parallel to the signal line on an other side of the signal line in the width direction,
- the plurality of third vias is arranged in a direction parallel to the signal line between the plurality of first vias and the signal line,
- the plurality of fourth vias is arranged in a direction parallel to the signal line between the plurality of second vias and the signal line,
- a ground layer disposed in the same layer as the signal line among the plurality of ground layers is provided as a reference ground layer,
- a ground layer disposed on a side furthest from the reference ground layer among the plurality of ground layers in the stacking direction is provided as a first long distance ground layer,
- a ground layer closest to the first long distance ground layer among the plurality of ground layers in the stacking direction is provided as a second long distance ground layer,
- the first via and the second via extend in the stacking direction to electrically connect the first long distance ground layer and the second long distance ground layer, or electrically connect the reference ground layer and the first long distance ground layer, and a distance between the first via and the second via is set to be equal to or more than a half wavelength of a secondary harmonic wave of the signal transmitted and received through the signal line and less than a wavelength of the secondary harmonic wave, and
- the third via and the fourth via extend in the stacking direction to electrically connect the reference ground layer and the second long distance ground layer, and a distance between the third via and the fourth via is set to be equal to or more than a half wavelength of a tertiary harmonic wave of the signal transmitted and received through the signal line and less than a wavelength of the tertiary harmonic wave.