A local oscillator for WCDMA band VII based on frequency multiplication

This work explores the generation of a local oscillator for WCDMA band VII based on frequency multiplication of a GSM reference. The frequency multiplier is based on a PLL, which includes a compact VCO based on a ring oscillator. A proper PLL design allows to sufficiently reject the relative high VCO phase noise, complying with the WCDMA requirements. The effectiveness of the proposed approach is proved with the design of the whole multiplier in a 90 nm CMOS technology. The generated oscillation ranges from 3 to 6 GHz, while the simulated phase noise is −120 and −144 dBc/Hz at a frequency offset of 0.6 and 20 MHz, respectively, dissipating 6.3 mW.