Third-Order Quadrature Oscillator With Arbitrary Phase Shift Generation and Amplitude Modulation Using MDXCCCTA

This work presents the realization of an electronically tunable third-order quadrature oscillator (TOQO) employing a current mode (CM) block, modified dual-X current controlled current conveyor transconductance amplifier (MDXCCCTA), and three grounded passive capacitors. The oscillator simultaneously provides two quadrature voltage outputs, two high-impedance quadrature current outputs, and one high-impedance current output with controllable amplitude. Further, the proposed circuit works as an arbitrary phase shift generator from 0 to ±90°. In addition, the realization generates amplitude modulation (AM) or amplitude shift keying (ASK) signals with controllable amplitude without affecting the condition of oscillation (CO) and frequency of oscillation (FO). The CO and FO are electronically tunable and can be controlled independently; moreover, an automatic control method is proposed to stabilize the CO and FO against the variation in relative amplitudes of quadrature signals when TOQO works as an arbitrary phase shift generator. It exhibits low phase error (0.22°), low % THD (0.78–0.88), low phase noise (−180 to −240 dBc), low sensitivity (
${ < }0.45{\%}$
), and low power consumption (1.08 mW); moreover, the circuit is vastly robust against tolerances in passive components and process, voltage, and temperature (PVT) corners as the deviations from nominal values are small (
${ < }0.8{\%}$
). The TOQO, furthermore, occupies a comparatively small layout chip area (
$7810 ~\mu \text{m}^{2}$
). It is a compact module providing quadrature, arbitrary phase shifted, and AM signals from the same realization. The proposed design can, therefore, be a handy module for instrumentation, measurement, and communication systems. Experimental results are presented to verify simulation and theoretical analyses.