Gyrator circuit simulating an inductance and use thereof as a filter or oscillator

An oscillator, characterized in that it comprises a resonant circuit of the LC-type in which an inductance L.sub.g is simulated by a gyrator circuit, said gyrator circuit comprising a first and a second transconductance amplifier A and B respectively having opposite conductances, which amplifiers are arranged in parallel between a first terminal a and a second terminal b and comprises a first capacitance C.sub.1 arranged between said first terminal a and a third terminal m, which gyrator circuit simulates an inductance L.sub.g arranged between said second terminal b and said third terminal m and comprises means for controlling the quality factor Q of said inductance, characterized in that the first transconductance amplifier A comprises two inverting amplifier stages P.sub.1 and P.sub.2 arranged in series, in that the second transconductance amplifier B comprises an inverting amplifier stage P.sub.3 and in that the means for controlling the quality factor Q comprises a first means P.sub.5 for influencing an output conductance g.sub.2 of the gyrator and a second means P.sub.6 for influencing the phase shift .phi. between an output current and a gyrator control voltage;

• said resonant circuit further comprising a second capacitance C.sub.2 connected between the second terminal b and the third terminal m;
• and the oscillation frequency is chosen by varying the capacitances C.sub.1 and C.sub.2.