滤波器
利用这些示例了解如何设计信号处理滤波器以去除或增强频率分量。
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模拟抗混叠滤波器
此示例展示了用于模数转换器的抗混叠滤波器的模拟实现。滤波器截止频率设置为 500 Hz ，以便匹配 1 kHz 的模数转换器采样频率。测试信号包含一个期望的 50 Hz 正弦波和一个 1100 Hz 的较高频率分量，在 1 kHz 模数转换器采样频率下无法捕获该频率分量。示波器显示了不应用抗混叠和应用抗混叠时捕获的信号。使用抗混叠滤波器时，正确测量了 50 Hz 正弦波振幅，振幅为 1，对应功率为 0.5 W（即对于 1 欧姆参考负载为 27 dBm）。
Band-Pass Filter Using Three Mutually-Coupled Inductors
An implementation of a band-pass filter using three mutually-coupled inductors. The model can be used to validate filter parameters which are chosen to provide a band-pass centered on 100MHz. A band-limited noise source is up-shifted by a 100MHz oscillator and applied to the filter. The response is then down-shifted by the oscillator. The model StopFcn callback takes FFTs of the source and response and estimates the filter frequency response.
Controllable Phase Shifter
An implementation of a first order phase shifting filter. The filter is characterized by the transfer function H(s) = (sC - gm1)/(sC + gm1). Double-click on the Set Design Parameters block to set the desired phase shift, amplitude of the input signal, and the frequency of the input signal. The block mask calls a function which sets the parameter values in the model workspace.
Fourth-Order Sallen-Key Lowpass Filter
An implementation of a fourth-order Sallen-Key low-pass filter using Operational Amplifiers (OPAs). The filter design parameters, cut-off frequency (f1) and DC gain (K), are specified by double-clicking on the Set Design Parameters block. Pass-band ripple is predefined to be 1dB using a Chebyshev response. The block mask calls a function which sets the parameter values in the model workspace.
Low-Pass Filter Using Operational Transconductance Amplifiers
Model a second-order active low-pass filter. The filter is characterized by the transfer function H(s) = 1 / ( (s/w1)^2 + (1/Q)*(s/w1) + 1 ) where w1 = 2*pi*f1, f1 is the cut-off frequency and Q is the quality factor. Double-click on the Set Design Parameters block to set parameters f1 and Q. The block mask calls a function which sets the parameter values in the model workspace.
