  This paper presents an analytical model on quadrature VCO (QVCO) phase noise
performance as well as a wide-tuning triple band QVCO RFIC design. The phase
noise model demonstrates the advantages of applying phase shift to quadrature
coupling for QVCO phase noise reduction and bi-model oscillation elimination.
As an example, we present a wide-tuning and low noise QVCO RFIC that contains a
bottom-series QVCO with bipolar transistors for oscillation and NMOS
transistors for coupling. The low-band and middle-band signals are generated
from the QVCO outputs and its 2nd harmonics, while the high-band signal is
obtained by frequency mixing. The tuning-range enhancement technique enables
the triple-band frequency generation in the range from 1.4GHz to 8.7GHz without
penalizing oscillator's phase noise. The proposed wide-band frequency
generation RFIC is implemented in a 0.18 {\mu}m SiGe BiCMOS technology with
0.6mm2 area. The measured phase-noise is -125.2, -119.5 and -108.8dBc/Hz at 1
MHz offset for the three bands, respectively.
