The article considers design features of the main modifications of analog interface for sensor systems, implemented on the base of differential difference op amps (DDA). Unlike classical structures of instrumentation amplifiers (IA) with junction coupling of stages, the suggested circuit solutions give small suppression of offset voltage (<= 30 mu V) and provide common-mode rejection more than -97dB in conditions of radiation and low temperature effects. Feeding of inherent compensation circuits of parasitic impedances of IA circuit according to the algorithm extends its bandwidth by a factor of 3-5. The article suggests new modifications of two-stage DDAs with higher voltage gain.