A dither-less all digital PLL for cellular transmitters

Frequency synthesizer for cellular transmitters demands low phase-noise both in-band and out-of-band. The first is necessary to implement wideband modulations (e.g. WCDMA), while the second to satisfy the challenging emission mask of GSM. Moreover a low level of fractional spurs must be ensured. The paper describes the first dither-less ADPLL capable to satisfy all these requirements. These results are achieved exploiting a highly linear 2-dimension Vernier TDC and a very fine frequency resolution DCO. Both building blocks heavily rely on digital calibration techniques to precisely and efficiently implement two-point modulation and spur cancellation in the presence of many implementation impairments.