1. An apparatus for designing a transformer in an integrated circuit, the apparatus comprising a processor; a user interface adapted to allow a user to input one or more desired characteristics of the transformer; wherein the one or more desired characteristics can include load impedances at primary and secondary coils of the transformer; wherein the processor is configured to determine sufficient optimal characteristics of the transformer to define the transformer for fabrication in the integrated circuit by performing the steps of combining the one or more desired characteristics with other preset characteristics of the transformer or the integrated circuit, defining a first model of the transformer with typical load impedances, simulating the first model having the combined characteristics to determine performance, processing results of the simulation to calculate performance with the load impedances specified by the user, further processing the results to obtain a mathematical model that includes tuning capacitors, drawing on a rule-set of expert knowledge relating to general dependency of at least one design criterion, such as a physical, geometrical or performance characteristic, with another design criterion in order to enable modification of the first model, and iteratively determining a design solution for the transformer through one or more simulations and modifications using the rule-set.