A.無窮大 B.零 C.約幾百千歐 D.約幾十歐姆
理想運(yùn)算放大器的開環(huán)電壓放大倍數(shù)是()
A.無窮大 B.零 C.約120dB
A.-2U B.-U C.+2U D.+U