A low-power wideband polar transmitter for 3G applications

So far all mainstream transmitters for WCDMA are of the direct upconversion type. This architecture is versatile but requires calibration of the imbalance in its quadrature branches and DC offset at its inputs, and it is vulnerable to mixer noise. We believe it consumes more power and chip area than is warranted, and propose the polar transmitter as an alternative. Although it has been widely discussed as the ideal transmitter for EDGE, the polar architecture has yet to make significant inroads there, let alone into wideband CDMA. We will describe new circuits that enable a compact, largely self-calibrated polar transmitter, whose lower power and chip area put it ahead of state-of-the-art direct upconversion transmitters.