PDF《Model X3DC21P1S》

90 degree phase difference. Doherty combiner functions as a coherent power combiner and supplies the

90 degree phase compensation. The following specification is defined with

50 ? port impedance at three ports for this condition. The return loss and the insertion loss in max power mode are not affected by the

50 ohm lossless port rotation mentioned in electrical spec table in page 1. The phase imbalance and the amplitude imbalance are not affected either since port rotation are taken off equally from the main and the peak amp port. Parameter Definition Mathematical Representation Return Loss The impedance match at the combining port to a 50? system. 20log Insertion Loss The combined power divided by the sum of input power under the perfect combining condition. 10log Phase Imbalance The phase difference between Peak-Combined path and Main-Combined path at = 2150MHz Phase C Phase Amplitude Imbalance The magnitude difference between Peak-Combined path and Main-Combined path. ? Low power condition Under low power condition, the Doherty operation turns off peak amplifier and requires main amplifier to be terminated with double of the optimum impedance (100 ?). In this configuration, Doherty combiner servers as an impedance transformer transforming

50 ? at combining port to

100 ? at main amplifier port. The following specification is defined under the port impedance condition of Port

1 (Combining Port)

50 ?, Port

4 (Main Amp Port)

100 ? and Port

3 (Peak Amp Port) open. With the peak amp left off, the extra line length in that port (see figure in page 2) acts as an open stub which shifts the low power mode return loss null and insertion loss. The offset line length needs to be adjusted taking the port rotation number into consideration so that the junction of

50 ? and

35 ? transmission line sees high impedance instead of the part edge. The return loss and the insertion loss defined below are after the offset line adjustments specified in the spec table. Parameter Definition Mathematical Representation Return Loss The impedance match of the

50 to100 ? transformer. 20log Insertion Loss The output power divided by input power. 20log Available on Tape and Reel for Pick and Place Manufacturing. USA/Canada: Toll Free: Europe: (315) 432-8909 (800) 411-6596 +44 2392-232392 Model X3DC21P1S Rev D PRELIMINARY Mounting Footprint Doherty Power handling Doherty power amplifiers are capable of amplifying the signals of high Peak to Average Ratio (PAR) with high efficiency. A 1:1 symmetrical Doherty architecture is typically used for signals of 6-10dB PAR. To evaluate power handling capability, the doherty combiner is analyzed in different conditions of varying PAR that the component would see in its lifetime. Condition 1: In symmetrical Doherty application, at average power condition, the Doherty amplifier works at back off mode and turns on only main amplifier with half of its full power capacity. The thermal condition of Anaren Doherty combiner is evaluated as an impedance transformer. X3DC21P1S can handle reliably for life

35 watts at main amplifier and

0 watts at peak amplifier when evaluated as impedance transformer. Condition 2: Doherty amplifier ramps up the main amplifier to 65% its full power capacity and peak amplifier to 30% of its full power capacity, outputting power roughly 3dB above the average. The thermal condition of Anaren Doherty combiner is analyzed as a coherent combiner and such power level is assumed continuously over entire life span of the component. Although conservative and limit the components power rating, it is done so to guarantee the life time of the components over high PAR signals. X3DC21P1S can handle reliably for life