Hitachi, Ltd.

Goro Hamamoto

Yutaka Uematsu

Tatsuyuki Ootani

Yohei Oshima

Keisuke Yamamoto

Masahiro Shiraishi

Shinsuke Onoe

Maya Hyakudomi

Jouji Matsushita

There is provided a printed wiring board including an outermost conductive layer that includes a plurality of conductive pads, a first conductive layer that includes a first inner-layer wiring and is stacked on the conductive layer, a second conductive layer that includes a second inner-layer wiring and is stacked on the conductive layer and the first conductive layer, a first signal via that connects one of the conductive pads and the first inner-layer wiring with each other, a second signal via connecting another one of the conductive pads and the second inner-layer wiring with each other, and a stitching via that is connected to a ground. The first inner-layer wiring and the second inner-layer wiring form a common wiring route in which the first inner-layer wiring and the second inner-layer wiring are stacked and disposed in a connection area in which the conductive pads are arranged.

Printed wiring board and information processing apparatus

In a printed wiring board, one transmitting circuit and N (N is an integer of 3 or more) receiving circuits are coupled by a multi-point wiring. First to N-th branch points are provided in sequence in the multi-point wiring having one end coupled to the transmitting circuit. Wirings branched at the respective branch points are coupled to the respective receiving circuits. Here, a wiring length from a coupling point of the transmitting circuit to a first branch point is configured to be longer than a wiring length from the first branch point to the second branch point. Wiring lengths between the adjacent branch points at and after a second branch point are configured to be shorter than the wiring length from the first branch point to the second branch point.

Main wiring including a plurality of differential transmission lines for transmitting differential signals is formed on a motherboard. Termination resistors, provided at both ends of each of the plurality of differential transmission lines, connect the plurality of differential transmission lines to each other. A plurality of daughter boards are connected in parallel to each other via the main wiring. A line characteristic impedance of each differential transmission line is higher than a termination resistance value, which is a resistance value of the termination resistor.

Control device

A signal transmission device has a multi-point wiring structure in which termination resistors are mounted on both ends of a cable, and a plurality of PCBs connected to the cable transmit a signal through the cable. The PCB of a host node includes: a connector connected to the cable; a transformer unit that is connected to the connector via a first PCB transmission line and insulates the connector; an RS 485 transceiver that is connected to the transformer unit via a second PCB transmission line and transmits the signal to the PCB of another node or receives the signal from the PCB of another node; and AC termination that is provided in at least one of the first PCB transmission line and the second PCB transmission line and suppresses resonance and antiresonance in a reflection frequency characteristic of noise.

Growing community of inventors

Tokyo, Japan

Goro Hamamoto