A Super-Harmonic Coupling QVCO Using a Frequency Doubler Circuit

This paper proposes a new super-harmonic coupled quadrature voltage controlled oscillator (QVCO), which oscillates at carrier frequency of 5.4GHz. The structure of the proposed circuit includes two complementary cross coupled oscillator with an extra frequency doubler circuit using mixing operation of triode region transistors to generate anti-phase second harmonic signals. Second harmonic injection takes place at center tap of the tank inductor. Simulation result based on a TSMC 0.18-μ$m$ CMOS technology shows −121.4dBc/Hz phase noise at 1MHz offset frequency, which shows 5dB improvement compared to the conventional complementary P-QVCO. In the proposed method, the quadrature accuracy has lower impact on phase noise. The proposed QVCO dissipates 2.5mA from a 1.8V supply and has a FOM of 189.3dB. The maximum simulated phase error is 3.7°in the presence of 1% tank capacitor mismatch.