A Current-Reused Back-Gate Coupling QVCO Using Transformer Feedback Structure

A current-reused back-gate coupling quadrature voltage-controlled oscillator (QVCO) using transformer feedback for K- band frequency applications is presented. The coupling scheme used to couple the two VCOs is a back-gate technique which removes the need for any extra coupling components that would degrade the phase noise performance and increase the power consumption. Utilizing current-reuse topology, which is inherently immune to the phase noise degradation, eliminates the second harmonic term at the common-source node of the conventional QVCOs. Moreover, the transformer feedback structure allows the QVCO to operate at low supply voltage. The tuning range of the proposed QVCO is 23.65-24.85 GHz, making the device applicable for K- band frequency wireless transceivers. The QVCO achieves a phase noise of -119.4 dBc/Hz at 1 MHz offset with a center frequency of 24 GHz as well as consumes 3.86 mW from a 0.8 V supply voltage. The QVCO is implemented in a standard 0.13 μm CMOS process with core area of 0.29 mm
²
.