A very low phase-noise ku-band resistively coupled VCO array in 0.25 μm SiGe:C BiCMOS

This paper presents a very low phase noise, Ku-band, differential coupled Voltage Controlled Oscillator (VCO) array implemented in the QUBIC4X 0.25 μm SiGe:C BiCMOS process of NXP semiconductors. The proposed circuit consists in two class-C type VCOs coupled through a resistive network. In these conditions, the phase shift is obtained by detuning the free-running frequencies of the two VCOs of the array. At 5 V supply voltage and a maximum power dissipation of 233 mW, the VCO array features a worst case phase noise of -99 dBc/Hz at 100 kHz frequency offset from a 13.5 GHz carrier. The VCO array can be tuned from 13.5 GHz to 14.75 GHz with a tuning voltage varying from 1 V to 4.5 V. Furthermore, thanks to the differential operation of the array, a continuously controlled phase shifting range from -80° to +78° and from +100° to +258° is obtained.