With the base grounded, transistor Q4 is a very high impedance.

当基极接地时，晶体管Q4便成为一个非常高的阻抗。

youdao

With the base grounded, transistor Q4 is a very high impedance.

当基极接地时，晶体管Q4便成为一个非常高的阻抗。

youdao