具有寄生极点的二阶电流模式滤波器的可调性
TUNING OF SECOND-ORDER CURRENT MODE FILTERS IN THE PRESENCE OF PARASITIC POLES
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摘要: 积分器寄生极点离主极点不是很远时,会引起全集成滤波器参数的偏差。文中分析了积分器有限直流增益和非主极点的影响,给出了二阶滤波器极点频率和品质因数的微变公式,研究了滤波器的可调控性。在此基础上,提出了增益可调型电流模式连续时间积分器,用这种积分器实现的滤波器能实现fp和Q的双调控。Abstract: The characteristics of fully integrated filters would deviate from the desired values in the presence of parasitic poles. The effects of the finite DC gain and non-dominant poles of the integrators on filter perfomance are analyzed, deviation fomulas of pole frequency and quality factor for the second-order filters are given, and tuning of filter characteristic parameters is dealt with. Moreover, a gain-tunable current-mode continuous-time integrator is presented. Both fp and Q can be tuned with the filter based on the integrator.
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