BAND PASS FILTER

• Main Authors: TANIMOTO HIROSHI, KOYAMA MIKIO
• Format: Patent
• Language: English
• Published: 07.09.1988
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRICITY; IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS

PURPOSE:To design the titled filter without adopting any approximation by connecting each one input terminal of two integration circuits to the other output terminal so as to constitute a loop circuit (biquad circuit) and using at least two sets of loop circuits. CONSTITUTION:Each component of inductors and capacitors of the circuit corresponds to an integration circuit and the integration circuits are coupled by a capacitor (Ck) to give/receive a signal of each loop circuit. In the integration circuit, capacitors required for the integration are all incorporated and a voltage at a control terminal (Vcontrol) is controlled to control the filter characteristic against the component variance. Moreover, the operational amplifier type is not employed for the integration circuit, but differential amplifiers having an excellent frequency characteristic is used to attain the high frequency operation. In integrating the integration circuit, when each component is designed to be of the same size, the relative accuracy among the components is enhanced. Thus, the circuit is subject to scaling so that the time constant of the integration circuit is all identical. The filter is constituted by having only to couple the loops of the integration circuits by the capacitors.