这只是尺度问题。随着系统级IC越来越大而复杂,它们也逐渐无法观察与激励。通过打线焊盘甚至探针都无法达到内部的节点。信号电压很小,噪声阈值极微,驱动强度可以忽略不计。当关键电路达到千兆频率时,已不可能在物理上获得片上信号的精确表述,即使可以用探针探到电路。 This is only a matter of scale. As system-level ICs become larger and more complex, they are also becoming less observable and motivational. Even the probe can not reach the internal node through the wire bonding pad. The signal voltage is small, the noise threshold is minimal, and the drive strength is negligible. When the critical circuit reaches gigahertz, it has not been possible to physically get an accurate representation of the on-chip signal, even though probes can be tapped into the circuit.