| 摘要 |
<p>RF power amplifier distortion can be accurately measured in the presence of multi-frequency input signals, by using a swept local oscillator (45) to tune RF input (20) and output (30) receivers. The power detected by the input receiver (20) is compared with a threshold associated with the carrier. Whenever the power detected by the input receiver (20) exceeds the threshold indicating that the input receiver is tuned on carrier energy and the signal path through the output receiver is blanked. The sweeping action combined with selective blanking of the output receiver (30) creates an adaptive notch filter, which allows for the direct measurement of low level distortion power in the presence of high power carriers. This distortion power is digitized and can be processed to control pre-distortion correction circuitry (14) or gain/phase adjustment circuitry (14) of a feed-forward error correction loop.</p> |
