| 摘要 |
PURPOSE:To observe the wave-form of a node to be observed by means of pads for external connection without forming pads for observation by a metod wherein each pad for external connection and a power source is connected through transistors, whose controlling input terminals are connected to wave-form observing nodes. CONSTITUTION:When observing the wave-form of the node (a) among wave-form observing nodes (a), (b), (c), signals are applied to pads 3-2, 3-3, etc. for external connection not had for common use with pads for observation, the node (a) is brought to an operating condition, and the signal wave-form is observed through a pad 3-1 for external connection used as a pad for observation. Since currents to a certain extent continually flow through field effect transistors 6-1, 6-2,... at that time, other MOS field effect transistors are each connected in series among a power source pad 5 and the field effect transistors 6-1, 6-2,..., and a switch can also be operated by signals from a pad for control formed in common with the MOS field effect transistors. |
