One way of explaining this is that pins configured as input make extremely small demands on the circuit that they are sampling , say equivalent to a series resistor of 100 megohms in front of the pin 我们可以这样来理解，在取样时，只需要在电路中通过非常小的电量，就好比在该接口前放置了100欧姆的电阻。
1 , 0 2 , 3 radio frequency connectors - part 29 : miniature r . f . coaxial connectors with screw - , push - pull , and snap - on coupling or slide - in rack and panel applications - characteristic impedance 50 ohms type 1 , 0 2 , 3 射频连接器.第29部分:用螺丝,压紧和搭接联接或滑动导轨和面板操作的小型r . f .同轴线连接件.电阻50欧姆的特性
