It is required to qualitatively design a circuitry device in which not only in a small-signal simulation but also in a large-signal simulation, loop oscillation and motorboating oscillation of an amplifier are precisely predicted to suppress oscillation without severing a loop or without inserting a circulator. To remove insertion loss due to a probe resistor Rx, a negative resistor −Rx/2 is arranged at both ends thereof. To prevent consumption of a DC bias in the probe, a DC block is applied. Further, to remove thermal noise caused by an actual resistor to reduce influence on a noise factor NF, the noise temperature (environmental temperature) of the actual resistor is set to zero Kelvin.