A “2 + 1” Cores Triple-Mode Oscillator

This paper proposes a millimeter-wave (mmW) oscillator with “ $2+1$ ” cores and triple operation modes to realize an octave-tuning range. An auxiliary core, comprising a switch and a negative transconductance cell, is introduced to the regular dual-core oscillator to generate a third mode with enhanced effective Q. This auxiliary core not only broadens the tuning range without compromising phase noise or chip area but also avoids the risk of introducing mismatch into two regular cores like triple-core oscillators. The demand for low interconnect resistance is relieved because of the merits of less core mismatch and extra magnetic injection lock path. The behavior of the proposed oscillator in different modes is studied analytically. A quantitative analysis of phase noise and interconnect resistance in the dual-core oscillator is presented and verified against circuit simulations. Implemented in a 65-nm CMOS process, the oscillator achieves a 72.24% tuning range from 16.35 to 35.48 GHz and a peak figure-of-merit of tuning range and area (FoM $_{\mathrm {TA}}$ ) of -217.07 dBc/Hz at 20.27 GHz with 1 MHz frequency offset. The chip operates from a 1 V supply with a power consumption from 6.3 to 21.76 mW and a core area of 0.075 mm2.