LMS-based calibration of an RF digitally controlled oscillator for mobile phones

We propose a least-mean square based gain calibration technique of an RF digitally controlled oscillator (DCO) in an all-digital phase-locked loop (ADPLL). The DCO gain of about 12-kHz/least significant bit is subject to process, voltage and temperature variations, but is tracked and compensated in real time. Precise setting of the inverse DCO gain in the ADPLL modulating path allows direct wide-band frequency modulation that is independent from the ADPLL loop bandwidth. The technique is part of a single-chip fully compliant Global System for Mobile Communications (GSM)/EDGE transceiver in 90-nm digital CMOS.