A GaN-on-SiC-based broadband driver amplifier operating in the C- and X-bands from 5 to 12 GHz has been demonstrated. The MMIC has a typical small signal gain of 29.7 dB with a ±1.4 dB gain ripple. The input and output return losses are better than 10.5 and 8.8 dB, respectively. The average P$${}_{s}{}_{a}{}_{t}$$ is approximately 2.65 W with an OIP3 of 37.7 dBm, while the large signal gain is 22 dB. This design is distinguished by its low output power ripple and the low large signal gain fluctuations observed across the full frequency range of interest. Consistent load impedance matching at the output stage for the whole frequency range enabled an output power ripple less than ±1.1 dB and a large signal gain ripple less than ±0.6 dB at 10 dBm input power. This allowed for an output power density of at least 2.68 W/mm across the broad frequency range of 5–12 GHz. The typical power-added efficiency is 26.4%. To the best of the authors' knowledge, this DA design exhibits the best combination of gain, output power density, gain ripple, output power ripple and output return loss in this frequency band.