Presentation on Digital Predistortion of Power Amplifiers - Agilent ...
Presentation on Digital Predistortion of Power Amplifiers - Agilent ...
Presentation on Digital Predistortion of Power Amplifiers - Agilent ...
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<strong>Digital</strong> Predistorti<strong>on</strong> - 22<br />
Feedback Error Signal for Predistorter<br />
I I error error signal<br />
signal<br />
PA PA Output<br />
Output<br />
Q error error signal<br />
signal<br />
adaptati<strong>on</strong> adaptati<strong>on</strong> parameter<br />
parameter<br />
Input<br />
Input<br />
<strong>Digital</strong> Predistorti<strong>on</strong> <strong>of</strong> <strong>Power</strong> Amps<br />
June, 01<br />
Page 22<br />
The complex gain functi<strong>on</strong>’s table entries are c<strong>on</strong>tinuously updated by m<strong>on</strong>itoring the error<br />
vector. The input signal is inverted before being summed with the measured power amplifier<br />
output signal. In this particular example, because we are using a behavioural model for the<br />
power amplifier the feedback delay is c<strong>on</strong>stant and has been taken into account. We have<br />
used the linear c<strong>on</strong>vergence adaptati<strong>on</strong> technique, where the adpatati<strong>on</strong> parameter has been<br />
set to -0.1. The resultant I and Q error signals are used to update the respective RAM Lookup<br />
tables.
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