设计了一种基于OTA的有源Gm-C复数带通滤波器,用以实现射频前端芯片中的中频滤波和镜像抑制功能,该滤波器采用Gyrator结构,将低通原型滤波器中的集总电感用有源电感进行替换,并依据复数变换理论,对浮地电容和接地电容进行复数变换,实现带通滤波器。滤波器中心频率为4.1MHz,1dB带宽2MHz,带内增益13.27dB,1.5倍带宽处抑制在40dB以上,镜像抑制度40dB。Gm-C滤波器集成度高,功耗低,适合于高频应用,是当前集成中频滤波器的热点。
An active Gm-C complex bandpass filter was proposed for front-end IC to achieve the functions of IF filter and image signal rejection. The construction of gyrator was used to instead of the inductor in prototype filter with the active inductor. Complex bandpass filter was achieved by translating the floating and grounded capacitors to complex frequency domain. The central frequency of the filter is 4.1 MHz with 2 MHz bandwidth and 40 dB outband rejection. The IMR is about 40 dB. The excellence of the Gm- C filter such as high integration, low power and high frequency is considered the hot points of the IF filter recently.