A Stochastic Analysis of Signal Sharing in a Bandpass Nonlinearity

When constant-amplitude signals and noise constitute the input to a bandpass device exhibiting a nonlinear input-output power characteristic and AM/PM conversion, the relative signal levels may change and intermodulation (IM) products are produced. A new and totally general method of evaluating the complex Fourier coefficient of any desired output component is presented. The analysis is based on repeated extraction using expected values of output signals dependent on one or more of the input signals, and makes use of joint envelope-phase probability distributions of the input conditioned on given signal phases. Several analytical examples demonstrating the application of the method and its advantages are discussed. Numerical results are presented for 2, 4, and 100 equal carriers into several types of soft limiters with quadratic AM/PM conversion.