Compatible integration of detectors and readout electronics on the same silicon substrate is of growing interest. As the methods of microelectronics technology have already been adapted for detector fabrication, a common technology basis for detectors and readout electronics is available. CMOS technology exhibits most attractive features for the compatible realization of readout electronics when advanced LSI processing steps are combined with detector requirements. The essential requirements for compatible integration are the availability of high resistivity (100)-oriented single crystalline silicon substrate, the formation of suitably doped areas for MOS circuits and the isolation of the low voltage circuit from the detector operated at much higher supply voltage. Junction isolation as a first approach based on present production technology and dielectric isolation based on an advanced SOI-LSI technology are discussed as the most promising solutions for present and future applications, respectively.