| 摘要 |
<p>A predistorter for linear amplification of a complex modulated signal is disclosed having an input stage, an envelope detector for measuring the amplitude of an RF signal and a predistorter controller. When the envelope detector outputs a signal, the signal is first differentiated with respect to time and the signal is then second differentiated with respect to time by differentiation circuitry. The first and said second derivatives are weighted and summed with the derivatives being used to effect a look ahead function. A look-up table having stored values of attenuation and phase shift is used to effect the required change in attenuation and phase shift to improve the amplifier linearity.</p> |
