Quadrature oscillators using CCIIs

Three third-order quadrature oscillators are proposed. Outputs of two sinusoids with 90 degrees phase difference are available in each quadrature oscillator circuit. The oscillation condition and oscillation frequency of each proposed quadrature oscillator are orthogonal controllable. All proposed circuits employ only grounded capacitors. The use of only grounded capacitors is ideal for integration. Experimental results are included to confirm the theoretical analysis.