Control Loop Structure for Phase Correction
Original Publication Date: 2001-Oct-01
Included in the Prior Art Database: 2003-Jul-23
Ralf Wendler: AUTHOR [+2]
The principle of operation of the control loop struc- ture for phase correction is explained in the following text.
Information / Kommunikation
einge- Control Loop Structure for Phase
Idee: Ralf Wendler, Berlin;
Jörg Braune, Berlin
The principle of operation of the control loop struc-ture for phase correction is explained in the followingtext.
The output signal of the pre amplifier (1) is undis-torted because pre amplifier (1) works as class Aamplifier. If the final stage input power increases andthe output power approaches to the 1dB compressionpoint the output signal is distorted.
This distortion causes two effects. The amplitudegain becomes smaller and the phase differencechanges between output and input of the final stage.
The amplitude problem is solved by an digital am-plitude predistortion, which uses look up tables inorder to correct the amplitude gain.
The phase difference problem is solved by the loopstructure, which is displayed in the schematic (seepic.1). If the phase angle is changing at the outputthen the power probe (9) delivers the changed phaseto the phase detector (8). The undistorted signalreaches phase detector (8) via power probe (2), thedelay line (5) and an limiter amplifier (7). The delayline (5) compensates the additional delay caused bythe signal path via phase shifter (3), final stages,power probe, additional line and limiter amplifier. Inresult the signal delay is equal in both pathes to thephase detector.
The principle operation is as follow. If an phase de-viation appears at the o...