  Dynamic nuclear polarization (DNP) is an NMR hyperpolarization technique that
mediates polarization transfer from highly polarized unpaired electrons to
NMR-active nuclei via microwave (mw) irradiation. The ability to generate
arbitrarily shaped mw pulses using arbitrary waveform generators opens up the
opportunity to remarkably improve the robustness and versatility of DNP, in
many ways resembling the early stages of pulsed NMR. We present here novel
design principles based on single-spin vector effective Hamiltonian theory to
develop new broadband DNP pulse sequences, namely an adiabatic XiX-DNP
experiment and a broadband amplitude modulated signal enhanced (BASE)
experiment. We demonstrate that the adiabatic BASE pulse sequence may achieve a
DNP $^{1}$H enhancement factor of $\sim$ 360, a record that outperforms all
previously known pulsed DNP sequences at $\sim$ 0.35 T and 80 K in static
solids. The bandwidth of the BASE-DNP experiments is about 3 times the $^{1}$H
Larmor frequency ($\sim$50 MHz).
