Low frequency dithering technique for linearization of current mode class D amplifiers

Traditionally, dithering has been used to avoid unwanted non-linear effects in transmitter amplifiers. According to conventional understanding, such techniques require a high frequency dithering signal, i.e., dithering frequencies larger than the signal frequency. A problem with this approach is that it results in a reactive power loss that increases with the dithering frequency. In one aspect, the present invention provides an improved transmitter amplifier in a digital communication system. Surprisingly, the transmitter amplifier employs dithering at a frequency lower than the signal frequency. Using this technique, a hard nonlinear characteristic can be linearized using a dither signal component whose main frequency is at least twice the bandwidth of the input band-pass signal. The input and dithering frequencies should be incommensurable. To achieve increased robustness and augmented linearity, the amplifier is preferably implemented with negative feedback.