A Novel High FOM Super-Harmonic Coupling QVCO Using Tail Injection Technique

• Published in: Electrical Engineering (ICEE), Iranian Conference on pp. 64 - 69
• Main Authors: Jafari, B., Esmaeeli, O., Sheikhaei, S.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01-05-2018
• Subjects: CMOS; Common-source node; Couplings; Harmonic analysis; LC cross-coupled oscillator; Phase noise; Power demand; Power harmonic filters; QVCO; Super-harmonic coupling; Tail transistor; Transistors
• ISBN: 1538649144; 9781538649145
• DOI: 10.1109/ICEE.2018.8472715

In this paper, a novel super-harmonic coupling technique for generating quadrature outputs is presented using complementary LC cross-coupled structure as the core oscillator. It is performed by connecting the top tail transistor gate terminal of the I oscillator to the bottom common-source node of the Q oscillator, and vice versa. Therefore, the second harmonic currents are injected through each tail transistor to the core oscillator with antiphase relation. The quadrature operation of the proposed QVCO are mathematically proved and its phase noise and phase error performances are investigated analytically. The proposed and conventional parallel (P)-QVCO are designed at the frequency range of 4.12-4.34GHz in 0.18\mu\text{m} CMOS technology with same power consumption of 4.75mW. The technology offered symmetrical spiral inductors are used in all tank circuits with a quality factor of 12. The two QVCOs are simulated using Cadence Spectre-RF simulator with same sizing and power consumption. The simulation results confirm quadrature operation of the proposed QVCO and show -125.1dBc/Hz phase noise at 1MHz offset from 4.12GHz carrier frequency for the proposed QVCO, that compared to the P-QVCO, 7.3dB phase noise improvement is achieved. The maximum phase errors of the proposed and conventional QVCOs are 4.6° and 3.15°, respectively for 1% tank capacitor mismatch. The proposed QVCO has a FOM of 190.6dB.