| abstract |
A gyrator circuit usable in a resonant filter circuit comprises a first and a second transconductance amplifier circuit, A and B, respectively, having opposite conductances, which amplifiers are arranged in parallel between a first terminal a and a second terminal b and comprise a first capacitance C1 arranged between said first terminal a and an earth terminal m, which gyrator circuit simulates an inductance Lg arranged between said second terminal b and said earth terminal m and comprises means for controlling the quality factor Q of said inductance, characterized in that the first transconductance amplifier circuit A comprises two series-connected inverting amplifier stages P1 and P2, in that the second transconductance amplifier circuit B comprises an inverting amplifier stage P3, and in that the means for controlling the quality factor Q comprise a first means P5 for influencing the output conductance q2 of the gyrator and a second means P6 for influencing the phase shift between the output current and the control voltage of the gyrator. |