Integration of the power amplifier together with signal processing in a transmitter is still missing in demanding RF commercial products. Issues preventing PA integration include LO pulling phenomena, thermal dissipation, and power efficiency. In this work we investigate high efficiency watt range Class-E PAs and integrated baluns. In particular, insights in the design of a fully differential cascode topology for high efficiency and reliable operation are provided and a narrowband lumped element balun, employing minimum number of integrated inductors for minimum power loss, is introduced. Two versions have been manufactured using a 0.13 mum CMOS technology. The first comprises the driver, and a differential PA connected to an external low-loss commercial balun. Experiments prove 31 dBm delivered output power, with 58% PAE and 67% drain efficiency, at 1.7 GHz. The second version adopts the same driver and PA and also integrates the balun. Experiments prove 30.5 dBm delivered output power, with 48% PAE and 55% drain efficiency, at 1.6 GHz.