Fine tuning of switching frequency for minimal distortion in high frequency PWM systems

A new method for evaluating and minimizing inband and out of band spurious intermodulation, in a naturally sampled PWM, is introduced and theorized. The proposed fine tuning method is based on solution of a set of linear inequalities, which are a function of RF and switching frequencies. The equations can be solved through linear programming techniques. A prototype voltage mode class-D amplifier has been designed and realized in 65 nm CMOS technology for verification purposes. Measurement results confirm the accuracy of the proposed tuning method for prediction of nonlinear metrics.