| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an active capacitor wherein a primary all-pass type 90-degrees phase-advanced stage or 90-degrees phase-delayed stage is formed using discrete elements without using op amplifiers, thereby making it possible to enhance a usable frequency band. <P>SOLUTION: The active capacitor comprises an input terminal 1(1), a primary all-pass type 90-degrees phase-advanced stage 3 constituted of the discrete elements, and a phase inversion amplifying stage 4 and includes a constitution in which a signal supplied to the input terminal 1(1) is inputted to the primary all-pass type 90-degrees phase-advanced stage 3, a 90-degrees phase-advanced signal obtained at its output is inputted to the phase inversion amplifying stage 4 subsequent to the primary all-pass type 90-degrees phase-advanced stage 3 and phase-inversion amplified thereat, and an output produced from the phase inversion amplifying stage 4 is feedback-coupled to the input terminal 1(1). The resistance value of a load resistor 4(2) of the phase inversion amplifying stage 4 is adjusted in such a manner that the signal gain between an input end 3i of the primary all-pass type 90-degrees phase-advanced stage 3 and an output end 4o of the phase inversion amplifying stage 4 is brought to 1, whereby the active capacitor is configured so as to exhibit an equivalent capacitor when the inside of the circuit is seen from the input terminal 1(1). <P>COPYRIGHT: (C)2008,JPO&INPIT |
