A 2-D Mode-Switching Quad-Core Oscillator Using E-M Mixed-Coupling Resonance Boosting

This article proposes a quad-core millimeter-wave (mm-wave) oscillator using E-M mixed-coupling resonance boosting. The mixed-coupling resonator is introduced to generate four reconfigurable resonances. The magnetic coupling and electric coupling are achieved by the symmetrically coupled transformer and coupling capacitor, respectively. A 2-D mode switch array is introduced to couple the quad-core and achieve the quad-mode switching without degrading the performance of the selected mode. Therefore, the reduction of phase noise and the extension of tuning range are achieved simultaneously. Meanwhile, the digitally controlled tail-resistor array is used to optimize the flicker noise up-conversion in wideband. Prototyped in 40-nm CMOS, the proposed oscillator exhibits a 73.2% tuning range from 18.6 to 40.1 GHz. The best phase noise at 1-MHz offset is -108.5 dBc/Hz, corresponding to an figure-of-merit (FoM) of 184.4 dBc/Hz and FoM_T of 201.7 dBc/Hz. The variation range of FoM over the whole frequency range is 3 dB. The 1/ f³ phase noise corner is 220-620 kHz.