自跟踪陷波器

AUTOMATIC TUNING LOW-PASS NOTCH FILTER

本文提出一种自动调谐陷波器,其陷波中心频率自动跟踪市电频率或某一外加干扰频率,以抑制其干扰.陷波器的谐振电路由LC组成,而电感L是用普遍阻抗转换器(GIC)来实现,GIC的端接电阻为压控MOS管电阻,因此可以用一电压控制此电阻以改变电感值,进而控制陷波频率.这种陷波电路可用于抑制市电频率的干扰噪声并防止测量或数据采集系统中前置放大器的饱和.实验结果表明在频率从45—55Hz,其陷波频率跟踪精度优于0.5Hz,而陷波深度(串模抑制比)为30—40dB.

An automatic tuning low frequency LC low-pass notch filter is developed. The generalized immittance converter (GIC) is used as a tunable inductor.The notch frequency of the filter can track the control frequency (the frequency of power supply or interference voltage) automatically. This filter can be used to eliminate the power supply noise and to prevent the preamplifier of measurement or data aquisition system from saturating caused by the power supply interference. Experimental results show that the frequency tracking error is less 晅han 0.5Hz in the range from 45Hz to 55Hz, and the notch depth of the filter, i.e. series mode rejection ratio, is 30-40 dB.