| US 7,415,252 B2 | ||
| Arrangement and method for digital predistortion of a complex baseband input signal | ||
| Björn Jelonnek, Ulm (Germany) | ||
| Assigned to Nokia Siemens Networks GmbH & Co. KG, Munich (Germany) | ||
| Appl. No. 10/555,811 PCT Filed Apr. 02, 2004, PCT No. PCT/EP2004/050425 § 371(c)(1), (2), (4) Date Nov. 07, 2005, PCT Pub. No. WO2004/100482, PCT Pub. Date Nov. 18, 2004. |
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| Claims priority of application No. 103 20 420 (DE), filed on May 07, 2003. | ||
| Prior Publication US 2007/0063769 A1, Mar. 22, 2007 | ||
| Int. Cl. H04M 7/00 (2006.01) | ||
| U.S. Cl. 455—114.3 [455/114.2; 455/130; 455/341] | 18 Claims |
| 1. A system for forming a predistorted signal from a broadband interpolated baseband signal for a transmit power amplifier
having n cascaded branches, comprising:
a predistortion unit provided for the first branch of the amplifier, the predistortion unit producing an estimated output
signal of the transmit power amplifier, the estimated output signal being formed based on memory effects of the amplifier,
the predistortion unit having an input receiving the interpolated baseband signal as an interim predistorted signal;
first and second adders, a distortion unit, a predistortion unit, and a digital filter provided for every jth branch of the
amplifier where 2≤j≤n, wherein:
the first adder has an input to receive the interpolated baseband signal via the distortion unit and an input to receive the
output signal from the predistortion unit of the j−1th branch, the first adder having an output producing an error signal
that is supplied to the digital filter,
the second adder proportionately forms an interim predistorted signal, the second adder having an input to receive the error
signal via the digital filter and an input to receive the interim predistorted signal from the j−1th branch, and
the predistortion unit receives the interim predistorted signal from the second adder and produces an output signal; and
a downstream filer connected to the output of the second adder of the nth branch, the downstream filter producing the predistorted
signal.
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