以电流I为响应，频率响应为 H ( j w ) = I ˙ U s ˙ = 1 r + j ( w L − 1 w C ) = 1 / r 1 + j w 0 L r ( w w 0 − 1 w 0 w L C ) = 1 r 1 1 + j Q ( w w 0 − w 0 w ) H(jw)=\frac{\dot{I}}{\dot{U_{s}}} =\frac{1}{r+j(wL-\frac{1}{wC})}=\frac{1/r}{1+j\frac{w_{0}L}{r}(\frac{w}{w_{0}}-\frac{1}{w_{0}wLC})}=\frac{1}{r}\frac{1}{1+jQ(\frac{w}{w_{0}}-\frac{w_{0}}{w})} H(jw)=Us​˙​I˙​=r+j(wL−wC1​)1​=1+jrw0​L​(w0​w​−w0​wLC1​)1/r​=r1​1+jQ(w0​w​−ww0​​)1​ H ( j w ) = H 0 w 0 Q ( j w ) ( j w ) 2 + w 0 Q ( j w ) + w 0 2 H(jw)=H_{0}\frac{\frac{w_{0}}{Q}(jw)}{(jw)^{2}+\frac{w_{0}}{Q}(jw)+w^{2}_{0}} H(jw)=H0​(jw)2+Qw0​​(jw)+w02​Qw0​​(jw)​ H 0 = 1 r H_{0}=\frac{1}{r} H0​=r1​ w 0 = 1 L C w_{0}=\frac{1}{\sqrt{LC}} w0​=LC ​1​

可见rLC串联谐振电路是一个带通电路

幅频响应曲线

由图可知Q值越大，曲线越尖锐，通频带越窄，选频特性越好。当W=Wo时，电路发生了谐振，幅频特性处于最大值。