| 摘要 |
PURPOSE:To attain a highly accurate control immune to noise by adding a high band attenuating characteristic to a frequency area in which the gain of a high frequency comes to be constant. CONSTITUTION:A transfer function H2(z) of a circuit constituted of coefficients b1 and b2, multiplying circuits 802 and 807, adding circuits 502 and 807 and a delaying circuit 806 is expressed by a formula I. By selecting the value of the coefficient b2 to the range of 0<b2<1, the low pass filter of a gain H2(o)=b1 T/(1-b2) is obtained and the frequency amplitude characteristic comes to be a characteristic C. The output of an adding circuit 808, namely, the output of a looping filter is the sum of adding circuits 803 and 804, and therefore, a transfer function Ho(z) of the output comes to be a formula 2. The frequency amplitude characteristic comes to be like a characteristic A to synthesize characteristics B and C. |
