Cadmium　zinc　telluride　detectors　are　the　highly　considered　for　room-temperature　hard　X-ray　and　gamma-ray　detection.　The　readout　systems　are　needed　in　the　detectors　to　output　the　detecting　data.　The　features　of　power　supplies　are　very　important　for　the　readout　circuits.　In　this　paper,　a　low-dropout　(LDO)　regulator　with　very　low　power　consumption　and　wide　load　variation　is　presented.　A　combining　compensation　method　which　includes　partially　controlled　load-tracking　technique　and　equivalent　series　resistance　compensation　technique　are　proposed　to　enhance　the　loop　stability　of　the　LDO　regulator.　Meanwhile,　high　dc　gain　is　obtained　to　improve　the　power　supply　ripple　rejection　(PSRR),　which　can　decrease　the　noise　from　the　power　supply.　The　prototype　LDO　chip　has　been　fabricated　and　tested　with　a　standard　0.18-mu　m　CMOS　technology.　The　measured　results　show　that　the　LDO　regulator　can　provide　up　to　150　mA　load　current　with　a　stable　output　voltage　of　2.8　V　under　an　input　voltage　scope　from　2.9　to　3.6　V.　The　measured　PSRR　is　up　to　-60　dB.　The　output　noise　spectral　densities　are　1.16　mu　V-RMS/root　Hz　and　211　nV(RMS)/root　Hz　at　1　and　100　kHz,　respectively,　at　load　current　of　150　mA.　Especially,　the　ultralow　quiescent　currents　of　5.2　mu　A　at　no　load　and　18.2　mu　A　at　full　load　bring　great　benefit　to　the　ultralow　power　integrated　readout　systems.