This paper presents a transmitter IC with two identical signal paths, including base-band amplifier, up-converting mixer, and power amplifier stages. The design is focused on wide modulation bandwidth, and the use of a resonatorless small die-area class-D power amplifier at cm-wave frequencies. This work also incorporates a local oscillator signal distribution network with phase tuning elements. The circuit is implemented in a 22-nm CMOS process, and the active die area is 0.8 mm2. Operation over the 6-20 GHz range of carrier frequencies through the transmission of both continuous wave (CW) and wideband quadrature phase shift keying (QPSK) modulated signals were verified with measurements. Results with 20/40/100, and 400 MHz modulation bandwidths are presented, and for instance for a 20-MHz QPSK modulated input signal the measured ACLR of the transmitter is 28 dBc and EVM is 5%.