Characterization of readout circuitry in a demonstrator chip of depleted CMOS active sensors

Depleted CMOS active sensors (DMAPS) in commercial multi-well CMOS technologies are an attractive detector choice for high-energy particle physics experiments, such as in the ATLAS High Luminosity Large Hadron Collider (HL-LHC). Since charge collection by drift is mandatory for such a harsh radiation environment, the application of high bias voltage to high resistive sensor material is needed. A demonstrator of a DMAPS (LFCPIX) has been fabricated in LFoundry 150 nm CMOS process on a substrate with a resistivity of >2 kΩ.cm. The chip size is 10 mm x 10 mm and the pixel size is 50 μm x 250 μm. ATLAS HL-LHC requires high time resolution of 25 ns and a total ionizing dose (TID) for the outer layers of ATLAS pixel detector is estimated as high as 50 Mrad. Ten flavors of readout circuitry are implemented in LFCPIX to investigate the timing performances and the radiation hardness. In the presentation, the characteristics of each readout flavors measured with electrical test pulses, radioactive sources and 2.5 GeV electron beam are shown.