| 摘要 |
PURPOSE:To improve transmission characteristic at a high frequency band by forming a bus of the back wiring board with a microstrip line. CONSTITUTION:The back wiring board 10 to be used at a high frequency band is provided with a shelf 30 accommodating a printed circuit board package 20 and a bus arranged on the rear side of the shelf 30 and interconnecting the printed circuit board packages 20. Then the bus is made of a microstrip line 12. Moreover, an impedance transformer 13 made of a microstrip line is provided at a connecting point between the printed circuit board package 20 and the bus made of the microstrip line 12. Thus, the transmission characteristic of the bus at the high frequency band is kept excellent and the impedance is matched at the connecting point by providing the impedance transformer 13, the deterioration in a waveform at a high frequency band is reduced to reduce malfunction of the device. |
