Abstract: Each realization of an electric circuit design defines a frequency response. For a test lot of the design, frequency responses are measured, each at a stable value of an environment parameter, wherein the totality of the values are distributed over a parameter range. Based on the measurements, a design-specific model is defined that describes a frequency response of the design in dependence of the environment parameter. For a unit in a main lot of realizations of the design, a unit-specific frequency response is measured at a stable value of the environment parameter; the model is fitted to the response, whereby a unit-specific model is obtained; data representing the unit-specific model is stored in association with the unit; and the unit is operated in conjunction with a compensation stage configured to determine a present value of the environment parameter and compensate drift in relation to a parameter-independent reference frequency response.