【单选题】Researchers have found that migrating animals use a variety of inner compasses to help them navigate. Some (1)_____ by the position of the Sun. Others navigate by the stars. Some use the Sun as (2)___...
【简答题】如题图为谐振功率放大器的电路图。其中,电容C 0 为旁路电容,R 1 为产生自偏压的电阻,RFC为高频扼流圈,R 1 为负载电阻,LC回路谐振于输入信号v i (t)的频率f c 。若晶体管的转移特性如题图所示,输入信号v i (t)=V im cos2πf c t。已知晶体管集电极电流余弦脉冲的峰值为20mA,流通角为60°,试计算自偏压V B 的值、电阻R 1 的值、输入电压的幅度V im 和...