1. An apparatus for designing a transformer in an integrated circuit, the apparatus comprising: a processor; and 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 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, processing the results to obtain a mathematical model that includes tuning capacitors by solving a constrained optimization problem to determine optimal values of the tuning capacitors based on the one or more desired characteristics and one or more optimization targets, whereby, given a transformer described by: a set of S-parameter matrices S, sampled at a set of frequencies F={f(1),. .. f(M}, and given an operating frequency f(i), with I in {1,. .. M}, a pair of primary/secondary loads Zp, Zs, which may be defined either as fixed complex numbers or as RL/RC series/parallel circuits, a pair of tuning capacitors c1, c2 are calculated such that insertion loss S12′(i) of the tuned circuit is maximal, subject to the following constraints: the capacitor values are restricted by c1 in [c1 min , c1 max ], and c2 in [c2 min , c2 max ] return losses are restricted by S11′<=RL —max , and S22′<=RL —max Bandwidth [f(i)−f_BW1, f(i)+f_BW2] of s12′ is restricted by F_BW1>=BW —min , and F_BW2<=BW —max inferring a modification of the first model based on general dependency of at least one design criterion, selected from at least a physical, geometrical or performance characteristic, with another design criterion, and iteratively determining a design solution for the transformer through one or more simulations and inferred modifications.