Power amplifiers having improved gate oxide integrity are disclosed. In particular, a dynamic asymmetric cascode bias circuit is used to provide a bias signal to a cascode power amplifier stage. The bias signal swings in synchronicity with an output signal from the power amplifier stage. By having this dynamic bias signal, the gate-drain stress on the device is reduced, preserving gate oxide integrity. Preserving gate oxide integrity helps preserve the operational profile and extend device life, providing an enhanced user experience.