This paper discusses the conceptual approach of a fully integrated polar transmitter for signal transmission in the sub-6 GHz frequency range. It investigates a compact differential inverse class-E topology as power output stage. To enable amplitude modulation without lossy DC-DC converters, a method for generating a pseudo-differential pulse width modulation is presented. A voltage controlled oscillator, phase shifters, a control interface and a current reference are also integrated on the chip. In laboratory measurements, the circuit with a compact chip area of 1.07 mm2 achieves a relative bandwidth of 71%, a maximum output power of 19.3 dBm and a PAE of 27% including bond wire and external balun losses at a low-voltage supply of 1V.