Presentation on Digital Predistortion of Power Amplifiers - Agilent ...
Presentation on Digital Predistortion of Power Amplifiers - Agilent ...
Presentation on Digital Predistortion of Power Amplifiers - Agilent ...
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
<strong>Digital</strong> Predistorti<strong>on</strong> - 5<br />
<strong>Power</strong> Amplifier Characteristics<br />
(W)<br />
(Normalized to Psat)<br />
(W)<br />
(Normalized to Psat)<br />
Measured Characteristics <strong>of</strong> a Typical Class AB <strong>Power</strong> Amplifier<br />
<strong>Digital</strong> Predistorti<strong>on</strong> <strong>of</strong> <strong>Power</strong> Amps<br />
June, 01<br />
Page 5<br />
N<strong>on</strong>linear amplifiers are characterized by measurement <strong>of</strong> their AM/AM (amplitude<br />
dependent gain) and AM/PM (amplitude dependent phase shift) characteristics. Not <strong>on</strong>ly<br />
are RF amplifiers n<strong>on</strong>linear, but they also possess memory: the output signal depends <strong>on</strong><br />
the current value <strong>of</strong> the input signal as well as previous values spanning the memory <strong>of</strong><br />
the amplifier. Class AB power amplifiers (~25% efficient) are more power efficient than<br />
Class A amplifiers (~5% efficient) . Class AB amplifiers exhibit gain roll-<strong>of</strong>f at low input<br />
powers as well as at saturati<strong>on</strong>. The loss <strong>of</strong> gain at low levels is due to the crossover<br />
regi<strong>on</strong> created by the push/pull transistor c<strong>on</strong>figurati<strong>on</strong>.
Change language