Electronic circuitry and in particular to circuitry for the cross feed cancellation of second order distortion

A method for the reduction of undesired second and higher order distortion products present in the signal(s) w.sub.1, w.sub.2, . . . , w.sub.M appearing at the M outputs of an imperfect nonlinear electronic device which has input signals u.sub.1, u.sub.2, . . . , u.sub.N applied to its N inputs, where N is an integer greater than unity and M is an integer greater than zero, and where input u.sub.n is applied to the n-th input, n being an integer lying between 1 and N inclusive, which comprises the steps of:

• incorporating cross-feed connections at the inputs of the non-linear electronic device, and
• generating by use of the cross-feed connections signals u .sub.1 ' u.sub.2 ', . . . , u.sub.N ' from the input signals u.sub.1, u.sub.2, . . . , u.sub.N such that at least one of the signals u.sub.1 ', u.sub.2 ', . . . , u.sub.N ' is a non-trivial function of at least two of the signals u.sub.1, u.sub.2, . . . , u.sub.N and such that the signal u.sub.N is a non-trivial function of at least the signal u.sub.N, where n is an integer between 1 and N inclusive, and
• applying the signals u.sub.1 ', u.sub.2 ', . . . , u.sub.N ' to the N inputs of the electronic device instead of applying the input signals u.sub.1, u.sub.2, . . . , u.sub.N directly to the N inputs so that the undesired second and higher order distortion products are reduced.