**Feedforward linearization**

This linearization technique is excellent in terms of bandwidth and IMD reduction. In order to generate the error signal, the power amplifier's output and the input signal are sampled using directional couplers and the first is then subtracted from the latter (see Fig. 7.). The error signal is then amplified and subtracted from the power amplifier's output to obtain the linear output signal. Since this technique utilizes an open loop concept, additional loop control is required in order to compensate the degradation of the power device over time to ensure the right settings of phase shift and gain for maximum linearity. IMD reduction of 20-40 dB can be achieved for bandwidth up to 100 MHz. The drawback of this technique is the complexity of the system.
