Method and arrangement for optimizing efficiency of a power amplifier
First Claim
1. An envelope tracking power amplifier having an amplifier stage, comprising:
- an envelope detector disposed to produce an envelope signal, said envelope signal representing an envelope of an input signal of the envelope tracking power amplifier, a non-linear filter disposed to filter the envelope signal so that a rise time of a peak in a waveform of the envelope signal is substantially preserved and a temporal duration of said peak is lengthened, said filter producing a filtered envelope signal, and a controllable supply unit disposed to determine a value of a supply voltage at least partly according to said filtered envelope signal and to produce the supply voltage for energizing the amplifier stage.
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Accused Products
Abstract
The invention relates to optimizing efficiency of a power amplifier of a transmitter. In a solution according to the invention a detected envelope (306) of an input signal of the power amplifier is filtered with a non-linear filter (307) that substantially preserves a rise time of a peak in a waveform of the envelope but lengthens a temporal duration of the peak. A filtered envelope is used as an input quantity (308) for a control system that controls a supply voltage of the power amplifier. For the control system it is easier to react to peaks of the filtered envelope than to the peaks of the envelope because the temporal duration of the peaks of the filtered envelope is longer than that of the peaks of the envelope.
72 Citations
22 Claims
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1. An envelope tracking power amplifier having an amplifier stage, comprising:
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an envelope detector disposed to produce an envelope signal, said envelope signal representing an envelope of an input signal of the envelope tracking power amplifier, a non-linear filter disposed to filter the envelope signal so that a rise time of a peak in a waveform of the envelope signal is substantially preserved and a temporal duration of said peak is lengthened, said filter producing a filtered envelope signal, and a controllable supply unit disposed to determine a value of a supply voltage at least partly according to said filtered envelope signal and to produce the supply voltage for energizing the amplifier stage. - View Dependent Claims (2, 3, 4, 5)
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6. A mobile communication device comprising:
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an envelope tracking power amplifier having an amplifier stage, an envelope detector disposed to produce an envelope signal, said envelope signal representing an envelope of an input signal of the envelope tracking power amplifier, a non-linear filter disposed to filter the envelope signal so that a rise time of a peak in a waveform of the envelope signal is substantially preserved and a temporal duration of said peak is lengthened, said filter producing a filtered envelope signal, and a controllable supply unit disposed to determine a value of a supply voltage at least partly according to said filtered envelope signal and to produce the supply voltage for energizing the amplifier stage. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A method for optimizing efficiency of an envelope tracking power amplifier having an amplifier stage, the method comprising:
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detecting an envelope signal that represents an envelope of an input signal of the envelope tracking power amplifier, producing a filtered envelope signal by filtering the envelope signal with a non-linear filter that substantially preserves a rise time of a peak in a waveform of the envelope signal and lengthens a temporal duration of said peak, determining a supply voltage value at least partly according to said filtered envelope signal, and setting a supply voltage of the amplifier stage to be the supply voltage value. - View Dependent Claims (13, 14, 15)
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16. A transmitter comprising:
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a base band stage disposed to produce a base band signal and an up-modulator disposed to up-modulate the base band signal, a power amplifier having an amplifier stage, an input signal of the amplifier stage being substantially an output signal of the up-modulator, an envelope detector disposed to detect from the base band signal an envelope signal that represents an envelope of the input signal of the amplifier stage, a non-linear filter disposed to filter the envelope signal so that a rise time of a peak in a waveform of the envelope signal is substantially preserved and a temporal duration of said peak is lengthened, said filter producing a filtered envelope signal, and a controllable supply unit disposed to determine a value of a supply voltage at least partly according to said filtered envelope signal and to produce the supply voltage for energizing the amplifier stage. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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Specification