A Wide Tuning Range Low-Phase-Noise Ku/Ka Dual Bands SiGe VCO Based on Transformer-Coupled Tank

A wide tuning range, low-phase-noise SiGe BiCMOS
LC
voltage-controlled oscillator (VCO) covering both the Ku- and Ka-bands is presented in this letter. The proposed VCO using a cross-coupled topology creates the fundamental harmonic from 14.35 to 17.86 GHz and the second harmonic, which is drawn from the common-mode point through a matched buffer, covering from 28.7 to 35.72 GHz. A transformer-coupled tank, which takes advantage of tank parasitics to create harmonic resonances, is used to reduce the phase noise (PN). The 5-bit binary-weighted capacitor bank is connected to the transformer secondary to create a wide tuning range, which is measured from 14.35 to 17.86 GHz (21.1%) and 28.7 to 35.72 GHz. Brilliant PN of −115.5 and −109 dBc/Hz at 1-MHz offset is measured at 14.53- and 29.1-GHz carrier frequencies individually. The proposed VCO with an extra output of the second harmonic exhibits little PN deterioration.