RC高通电路的频率特性 R U R+1/jOC 1+ljaRC 0R令1/RC=则f=12mRC 1+(f1/) g= rotan f1/∫超前 f≥10f20lgA =0 dB q≈0 几20g}4=201g0.7071=-3dBp=45° f≤0.1f20lg4l=-0gf/ q≈90° 66 二、RC 高通电路的频率特性 R C RC R U U Au  1 1/j 1 1/ j i o + = + = = • • • f f L 1 j 1 - = 令 1/RC = L则 fL = 1/2RC  = arctan f L / f 超前 1 ( / ) 1 2 L f f Au + =  f  10 fL 20lg|Au | = 0 dB   0 f = fL 20lg|Au | = 20lg0.7071 = -3 dB  = 45 f  0.1 fL 20lg|Au | = -20lg f / fH   90 R C Ui Uo • •