VCO gain calibration technique for GSM/EDGE polar modulated transmitter

Abstract

This paper describes a VCO gain calibration technique for the two-point modulation scheme using Delta-Sigma frequency synthesizer. The proposed technique enables PLL-based phase modulator to have wide bandwidth with good signal quality. A fully integrated GSM/EDGE polar modulated transmitter, implemented in a 0.13 mum CMOS process, is presented to show the feasibility of this calibration technique. After the calibration, it shows a margin of 8 dB to the spectrum mask at 400 kHz offset with EVM of 2%.