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. The output signal of the pre amplifier (1) is undis- torted because pre amplifier (1) works as class A amplifier. If the final stage input power increases and the output power approaches to the 1dB compression point the output signal is distorted.
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...