A source degenerated LC quadrature VCO (SD-QVCO) using 0.18-mu m SiGe BiCMOS
This letter presents a fully integrated BiCMOS quadrature voltage-controlled oscillator (QVCO). The QVCO consists of two nMOSFET cross-coupled oscillator stacked in series with source degenerated HBT transistors. SiGe HBT introduces low flicker noise compared to CMOS devices. To generate quadrature phase signals with strong coupling strength, the proposed design uses two MOS-coupled LC-tank cores instead of passive device-coupled cores. This source degeneration topology can improve the phase noise performance of the QVCO as compared to the sub-VCO. The proposed QVCO has been implemented with the TSMC 0.18 mu m SiGe 3P6M BiCMOS process, can generate quadrature signals in the frequency range of 4.52-5.05 GHz with core power consumption of 5.76 mW at the dc bias of 1.8 V. At 4.53 GHz, phase noise at 1 MHz offset is -124.52 dBc/Hz. The die area of the fabricated prototype is 0.453 x 0.898 mm(2).
source degenerated qvco bicmos mos-coupled lc-tank 0.18 mu m sige 3p6m