| 摘要 |
PURPOSE:To increase the attenuation factor and to accelerate the response properties, by combining a secondary band pass filter with a band-elimination filter. CONSTITUTION:Among various types of constitutions of a filter that extracts the specific frequency component, a band-elimination filter using a twin bridge circuit is effective in terms of a large attenuation factor. The twin bridge circuit consists of a T circuit comprising a resistance R3 plus capacitors C1 and C2 and another T circuit comprising resistances R2 and R1 plus a capacitor C3. For the transmission function of the twin bridge circuit, omegaO/omegaN is set at 4-5, where omegaO is the basic angle frequency of a denominator and omegaN is the root of a numerator, i.e., the frequency corresponding to zero point. Thus the attenuation factor at a high range can be set at a 20-30dB high level. On the other hand, the highest response is realized for a secondary filter by selecting the value of each element so that the denominator of the transmission function becomes a multiple root. |
