3.6 GHz VCOs for multi-band GSM transceivers

Two integrated 3.6 GHz VCO´s for multi-band GSM direct-conversion transceivers fabricated in a 0.25 µm CMOS technology are presented. Excellent phase-noise performance is achieved by minimizing noise generation in the active circuit and by suppressing noise injection from the bias circuit. Using switched-capacitors in the resonator a large effective tuning range is obtained. Measured phase-noise as low as -145 dBc/Hz at 3 MHz frequency offset and low power consumption compares favorably with previous published integrated VCO´s.