Quadrature voltage control oscillator with a linear tuning law

Abstract

New realisation scheme of linear voltage-controlled quadrature oscillator (QO) is proposed. The active building block is electronically tunable (ET) differential voltage current conveyor transconductance (gm) amplifier configured with current feedback amplifier and multiplication mode current conveyor devices. The designs are essentially tuned-inductor–capacitor oscillator, wherein the electronically variable lossless grounded inductor (L) had been simulated at suitable nodes of the active building block. Subsequently, with slight modification of the block, an ET floating-lossless immittance function generation is presented. Effects of device port mismatch error and parasitic capacitances are analysed. Albeit sensitivity relative to port mismatch error is negligible, the parasitic components tend to limit the higher-usable frequency range; appropriate design equations are derived for a true bilinear admittance function realisation and their applications to filter and sinusoid oscillator design are included. Experimental results on the QO with linear fo-tuning law are satisfactorily verified up to 8.7 MHz at low total harmonic distortion.