Multiband and Wide Dynamic Range Digital Polar Transmitter Using Current-Mode Class-D CMOS Power Amplifier

Abstract

Techniques are demonstrated to extend the power control dynamic range of a digitally-driven 0.15 um CMOS polar power amplifier to the degree needed for WCDMA handset applications. The output frequency can be tuned over the 0.75-2GHz range, using an on-chip band-switching resonator, and output power of 27-29 dBm is attained. By partitioning the switching PA into multiple 3-state unit cells, power dynamic ranges of 91 / 85 dB are achieved at 0.85 / 1.75 GHz while maintaining high efficiency. By introducing a buck converter that can act not only with pulse width modulation but also in charge sampling mode, the overall DC power consumption in the power back- off regime can be reduced by a factor of approximately 0.7.