Abstract: A signal transmission circuit includes a printed circuit board including a surface layer including a signal transmission path that transmits a signal, a signal line through hole that connects the signal transmission path with a signal layer arranged in an inner layer of the printed circuit board, a ground layer of the inner layer of the printed circuit board that forms a return current transmission path for the signal transmission path, and a ground through hole that is connected to the ground layer adjacent to the signal line through hole. A ground pattern including ground areas disposed with a certain distance therebetween and a side ground area connected with at least one end side of the ground areas is disposed at positions of both sides of the signal transmission path. The ground through hole is disposed to connect the ground pattern with the ground layer.

Abstract: A signal transmission circuit includes a printed circuit board including a surface layer including a signal transmission path that transmits a signal, a signal line through hole that connects the signal transmission path with a signal layer arranged in an inner layer of the printed circuit board, a ground layer of the inner layer of the printed circuit board that forms a return current transmission path for the signal transmission path, and a ground through hole that is connected to the ground layer adjacent to the signal line through hole. A ground pattern including ground areas disposed with a certain distance therebetween and a side ground area connected with at least one end side of the ground areas is disposed at positions of both sides of the signal transmission path. The ground through hole is disposed to connect the ground pattern with the ground layer.