测控电路课后习题答案(张国雄第四版)第4张（Measurement and control circuit after-school exercises answers (Zhang Guoxiong Fourth Edition) fourth）.docVIP

测控电路课后习题答案(张国雄第四版)第4张（Measurement and control circuit after-school exercises answers (Zhang Guoxiong Fourth Edition) fourth） The fourth chapter is signal separation circuit 4-1 briefly describe the filter function, classification and main characteristic parameters A filter is a circuit or processing system with frequency selection. According to the signal processing, filters can be divided into two types: analog filter and digital filter. According to the function filter, the filter can be divided into four categories: low-pass, high pass, band-pass and band stop. The main characteristic parameters of the filter include: 1) frequency parameters are as follows: the frequency of the filter passband cutoff frequency for bandpass boundary points and the transition zone, the signal gain decreased to a prescribed minimum. The stopband cutoff frequency band boundary points and transition zone for resistance, the signal loss (gain reciprocal) down to a prescribed minimum. The turnover frequency of signal power attenuation to the frequency (about 3dB), in many cases, often as a band or stopband cutoff frequency. When the circuit is not lossy, the natural frequency is its resonant frequency, and complex circuits often have multiple natural frequencies. 2) gain is not a constant gain and attenuation filter in the passband. For lowpass filters, the passband gain generally refers to the gain in time; the gain in the high pass refers to the gain at the center frequency. The band stop filter, should give the stopband attenuation, attenuation is defined as the reciprocal of the gain. The change of passband gain refers to the maximum change in the gain of each point in the passband. If dB is used, then the change of the gain dB value is considered. 3) damping coefficient and damping coefficient of quality factor is the characterization of filter frequency signal of the diagonal damping effect, is an indicator of the energy attenuation of said filter, and it is the real part of the p