双模式复数滤波器电路设计

Design of a Dual-Mode Complex Filter

采用0.18μm CMOS工艺,实现了一款中心频率和带宽可调节的OTA-C复数滤波器。通过设置控制字,可以控制复数滤波器的带宽和中心频率,形成窄带和宽带两种模式。滤波器的带宽设计为5 MHz和25 MHz,中心频率分别为4 MHz和15.4 MHz。窄带滤波器镜像抑制大于30dB(测试),宽带滤波器镜像抑制大于40 dB(仿真)。设计中,采用了基于VCO锁相环结构的片上频率修正电路。滤波器消耗的总电流分别为1.7 mA和2.5 mA。仿真结果与测试结果非常吻合。

An active OTA-C complex filter was implemented in 0. 18μm CMOS process. The filter can operate in two modes： narrow-band and wide-band modes, with different center frequencies and bandwidths. The dual-mode filter＇s bandwidths,centered at 4 MHz and 15. 4 MHz,are 5 MHz and 25 MHz. Image rejections for narrow-band and wide-band filters are greater than 30 dB and 47 dB, respectively. The tuning scheme adopted in this design is based on VCO phase-locked loop. The filter dissipates 1.7 mA and 2. 5 mA of power, respectively. The simulated and measured results are in good agreement.