Method for signal processing and a transmitting device with digital predistortion, in particular for mobile radio
First Claim
1. A method for signal processing, comprising:
- providing of at least one amplifier circuit characterized by at least one characteristic variable during operation;
providing a discrete-value and discrete-time modulation signal comprising a first component and a second component, and providing a carrier signal with an amplitude and a phase;
providing a plurality of selectable pairs of predistortion coefficients;
producing a power word that is a function of the first component of the modulation signal;
comparing the power word with a reference value and producing a first result or a second result in response thereto;
selecting a pair of predistortion coefficients from the plurality of selectable pairs as a function of the first component and a control word derived from the power word;
distorting the first component with a first coefficient of the selected pair of predistortion coefficients and distorting the second component with a second coefficient of the selected pair of predistortion coefficients when the comparison has produced the first result;
modulating the phase of the carrier signal with the distorted second component of the modulation signal when the comparison has produced the first result, or modulating the phase of the carrier signal with the second component of the modulation signal when the comparison has produced the second result;
modulating the amplitude of the phase-modulated carrier signal as a function of the distorted first component of the modulation signal when the comparison has produced the first result, or modulating the amplitude of the phase-modulated carrier signal with the first component of the modulation signal when the comparison has produced the second result; and
amplifying the modulated carrier signal by the at least one amplifier circuit.
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Accused Products
Abstract
A transmitting device with digital predistortion is disclosed. The device produces a power word derived from an amplitude component of a digital modulation signal and a desired output power. The power word is compared with a limit value, and depending on the result, one pair of predistortion coefficients is selected and distortion of a first and second component of the digital modulation signal is thus carried out. The phase and the amplitude of a carrier signal are then modulated with the distorted components. Selective distortion of the modulation signal is carried out by comparison of the power word with a limit value, when the signal quality or the linearity of the modulated carrier signal falls below a predetermined limit value. Otherwise, the predistortion unit can be switched off, and the power consumption can thus be reduced.
46 Citations
22 Claims
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1. A method for signal processing, comprising:
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providing of at least one amplifier circuit characterized by at least one characteristic variable during operation;
providing a discrete-value and discrete-time modulation signal comprising a first component and a second component, and providing a carrier signal with an amplitude and a phase;
providing a plurality of selectable pairs of predistortion coefficients;
producing a power word that is a function of the first component of the modulation signal;
comparing the power word with a reference value and producing a first result or a second result in response thereto;
selecting a pair of predistortion coefficients from the plurality of selectable pairs as a function of the first component and a control word derived from the power word;
distorting the first component with a first coefficient of the selected pair of predistortion coefficients and distorting the second component with a second coefficient of the selected pair of predistortion coefficients when the comparison has produced the first result;
modulating the phase of the carrier signal with the distorted second component of the modulation signal when the comparison has produced the first result, or modulating the phase of the carrier signal with the second component of the modulation signal when the comparison has produced the second result;
modulating the amplitude of the phase-modulated carrier signal as a function of the distorted first component of the modulation signal when the comparison has produced the first result, or modulating the amplitude of the phase-modulated carrier signal with the first component of the modulation signal when the comparison has produced the second result; and
amplifying the modulated carrier signal by the at least one amplifier circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A transmitting device with digital predistortion, comprising:
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a signal processing device configured to produce and emit a discrete-value and a discrete-time modulation signal with a first component and a second component, and further configured to emit a power control signal which is derived from the first component to a control output;
a predistortion device, comprising;
a first signal path configured to pass the modulation signal to an output thereof;
a second signal path including switching elements for distortion of the modulation signal as a function of a signal present at a control input and as a function of the first component;
wherein the predistortion device is configured to activate the first or the second signal path as a function of the signal at the control input and output a selectively predistorted modulation signal;
a modulation unit configured to modulate a phase of a carrier signal with a portion of the selectively predistorted modulation signal;
at least one variable gain amplifier circuit whose input is coupled to an output of the modulation unit;
a power control unit connected to a control output of the signal processing device, with a first output connected to a control input of the predistortion device, and a second output coupled to the at least one amplifier circuit for gain adjustment, the power control unit configured to emit a control signal for predistortion at the first output, and a gain adjustment signal at the second output based on the power control signal applied to its input. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification