The phase of the impedance should also be controllable. The impedance used is the output impedance (Z) of a voltage/current converter (D) which is followed by a controllable amplifier (VCA) for influencing the absolute value of the impedance (Z). The converter (D) forms a feedback for the amplifier (VCA). To be able to select the phase of the impedance (Z), a reference impedance (C) is inserted into the feedback. The impedance value of this reference impedance (C) can be selected and determines the phase of the impedance (Z) of the two-terminal network. Applicable to tunable filters or wherever an impedance is needed which can be preferably controlled by a voltage. <IMAGE>
