第5章频率响应 A(|=14=07074 (5-3) 4()=4n|=0707 (5-4) BH=fn-f1≈fn (5-5) Gn=20gA(n)|=20gA|-3B (5-6) G2=20gA()|=20gA|-3B G·BW=4BW|≈=An·fn (5-7 ac第5章 频率响应 u I u I H L u L u I H u H u I H L H u L u I u I u H u I u I G BW A BW A f G A j f A dB G A j f A dB BW f f f A j f A A A j f A A  =    = = − = = − = −  = = = = 20lg ( ) 20lg 3 20lg ( ) 20lg 3 0.707 2 1 ( ) 0.707 2 1 ( ) (5―3) (5―4) (5―5) (5―6) (5―7)