Transmission line substrate and electronic device

A transmission line substrate comprising:

• a stacked body that includes a first surface and a second surface facing each other, includes a first face, a second face, a third face, a fourth face, and a fifth face, and includes a plurality of insulating base material layers stacked on each other;
• a first signal line that is provided on any one of the plurality of insulating base material layers;
• a second signal line that is provided on any one of the plurality of insulating base material layers;
• a third signal line that is provided on any one of the plurality of insulating base material layers;
• a first ground conductor that is provided on any one of the plurality of insulating base material layers;
• a second ground conductor that is provided on any one of the plurality of insulating base material layers;
• a third ground conductor that is provided on any one of the plurality of insulating base material layers;
• a fourth ground conductor that is provided on any one of the plurality of insulating base material layers;
• an interlayer connection conductor including a first interlayer connection conductor that is provided in any one of the plurality of insulating base material layers, a second interlayer connection conductor that is provided in any one of the plurality of insulating base material layers, and a third interlayer connection conductor that is provided in any one of the plurality of insulating base material layers;
• a plurality of first external connection electrodes that are provided on at least one of the first surface or the second surface, and are connected to the first signal line;
• a plurality of second external connection electrodes that are provided on at least one of the first surface or the second surface, and are connected to the second signal line;
• a first transmission line including the first signal line, the first ground conductor, and a first insulating base material layer among the plurality of insulating base material layers, the first insulating base material layer being interposed between the first signal line and the first ground conductor;
• a second transmission line including the second signal line, the second ground conductor, and the first insulating base material layer being interposed between the second signal line and the second ground conductor;
• and
• a third transmission line including the third signal line, the second ground conductor, and a second insulating base material layer among the plurality of insulating base material layers, the second insulating base material layer being interposed between the third signal line and the second ground conductor;
• wherein
• the first signal line is provided on the second face;
• the second signal line is provided on the first face different from the second face on which the first signal line is provided and extends in parallel or substantially in parallel with the first signal line when viewed in the stacking direction;
• the third signal line is provided on the fifth face different from the second face on which the first signal line is provided and extends in parallel or substantially in parallel with the first signal line when viewed in the stacking direction;
• the first ground conductor is provided on the first face, and is overlapped with the first signal line when viewed in the stacking direction;
• the second ground conductor is provided on the second face, and is overlapped with the second signal line and the third signal line when viewed in the stacking direction;
• the third ground conductor is provided on the third face different from the fifth face, is disposed so as to face the first ground conductor across the first signal line with respect to the stacking direction, and is overlapped with the first signal line and the third signal line when viewed in the stacking direction;
• the fourth ground conductor is provided on the fourth face different from the first face, and is disposed so as to face the second ground conductor and the third signal line across the second signal line with respect to the stacking direction;
• the first interlayer connection conductor electrically connects the first ground conductor and the second ground conductor;
• the first interlayer connection conductor is located between the first signal line and the second signal line when viewed in the stacking direction, and extends from the first ground conductor to the second ground conductor;
• the second interlayer connection conductor electrically connects the second ground conductor and the third ground conductor;
• the second interlayer connection conductor is located between the first signal line and the second signal line when viewed in the stacking direction;
• the third interlayer connection conductor electrically connects the first ground conductor and the fourth ground conductor;
• the third interlayer connection conductor is located between the first signal line and the second signal line when viewed in the stacking direction, and extends from the first ground conductor to the fourth ground conductor;
• the plurality of first external connection electrodes are respectively disposed in a vicinity of opposite ends of the stacked body in a transmission direction in which the first signal line and the second signal line extend;
• the plurality of second external connection electrodes are respectively disposed in a vicinity of opposite ends of the stacked body in the transmission direction;
• the stacked body includes a first region and a second region separated by the interlayer connection conductor when viewed in the stacking direction;
• and
• a number of signal lines provided in the plurality of insulating base material layers differs between the first region and the second region.