A Wideband CMOS Linear Digital Phase Rotator

This paper presents a 10-bit wideband Cartesian phase rotator with a novel linear digital VGA implemented in a 0.13 um CMOS process. The VGA topology is robust to device modeling uncertainties and PVT variations. The system provides 7.8 dB voltage gain with -3 dB bandwidth of 7.6 GHz. A maximum phase error of 2deg has been achieved for a phase shifting range of 360deg with 32 phase steps of 11.25deg. The capability to compensate for mismatched quadrature inputs is also demonstrated.