| 摘要 |
An analog envelope shaper within an envelope tracking power amplifier system detects an envelope voltage of a transmission signal and generates a shaped envelope amplifier control signal based upon a programmable threshold, below which the output does not fall, and a plurality of different voltages centered around a corresponding threshold input voltage, a selectable spacing of which controls the shape of the transition between negative clipping and linear regions of the envelope detector output function. The programmable features and the resulting piecewise linear shaping allow for tailoring of the envelope response to balance linearity and efficiency, without negating the efficiency benefits of envelope tracking power amplification. Since the analog envelope shaper employs no high speed data converter functions, the resulting power dissipation will be substantially less than digital designs. |
