Precision analog integrator with voltage hold

In some applications, like a magnetization and demagnetization of ordinary and superconducting magnets driven by the voltage controlled current sources, it is desirable to change the voltage smoothly and linearly toward an adjusted value and then hold this value in time. A circuit is presented that allows: (i) the slow, smooth, and linear change of the integrator output voltage without steps and (ii) the ability to hold the output voltage at a value given by a reference source. In a hold regime, the output voltage is stabilized by a negative feedback. A stability of one part of 10(5) at the output voltage of 2 V was achieved over a 12 h period.