An Efficient and Compact Mixed-Mode TOQO using Single CFDITA

A novel electronically adjustable quadrature oscillator of third-order type is introduced in this paper. It is a mixed-mode oscillator as it generates two voltage and two current output signals. The proposed design uses a single current fol-lower differential input transconductance amplifier along with three capacitors and two MOS-resistors. The use of all grounded capacitors makes it the best choice for modern in-tegration technology. The paper includes detailed ideal, non-ideal and parasitic studies, frequency stability and phase noise analyses. In addition of simpler design and integration sup-port, the proposed oscillator design has the features of good operational frequency (22.4 MHz), low total harmonic distor-tion (<1.7%), low operating supply voltages (±1 V) and low power consumption (0.14 mW). The theoretical aspects are validated by the post-layout simulation using gpdk 180 nm technology through Cadence Virtuoso tool. The layout of the used active device, current follower differential input trans-conductance amplifier occupies an area of 19 µm × 27 µm. Experimental verification using off-the-shelf ICs LM13700 and AD844 is also performed to check the practicality of the proposed design. The application perspective of the proposed third-order quadrature oscillator in terms of quadrature am-plitude modulation (QAM) is also explored.