  Monolithic Active Pixel Sensors (MAPS) have been developed since the late
1990s employing silicon substrate with a thin epitaxial layer in which
deposited charge is collected by disordered diffusion rather than by drift in
an electric field. As a consequence the signal is small and slow, and the
radiation tolerance is below the requirements for LHC experiments by factors of
100 to 1000. We developed fully depleted (D)MAPS pixel sensors employing a 150
nm CMOS technology and using a high resistivity substrate as well as a high
biasing voltage. The development has been carried out in three subsequent
iterations, from prototypes to a large pixel matrix comprising a complete
readout architecture suitable for LHC operation. Full CMOS electronics is
embedded in large deep n-wells which at the same time serve as collection nodes
(large electrode design). The devices have been intensively characterized
before and after irradiation employing lab tests as well as particle beams. The
devices can cope with particle rates seen by the innermost pixel detectors of
the LHC pp-experiments or as seen by the outer pixel layers of the planned
HL-LHC upgrade. They are radiation hard to particle fluences of at least
$10^{15}~\mathrm{n_{eq}/cm^2}$ and total ionization doses of at least 50 Mrad.
