Multigigahertz voltage-controlled oscillators in advanced silicon bipolar technology

Relaxation-type monolithic silicon bipolar voltage-controlled oscillators (VCOs) with center frequencies ranging from 1.5 to 5 GHz are described. The maximum oscillating frequency achieved is 7.4 GHz. The VCOs dissipate about 70 mW from a 3.6-V supply, including the output buffer and voltage-to-current converter stages. Two types of on-chip timing capacitor structure and various configurations used in achieving these results are described. A wide tuning range sufficient for covering the normal process tolerances and supply variations expected in a practical environment was achieved. The circuits were fabricated in an advanced 0.8-μm double-poly self-aligned bipolar technology