US 10,594,269 B2Granted

Crest factor reduction in power amplifier circuits

AssigneeShenzhen Goodix Technology Co., Ltd.

InventorsAmir Dezfooliyan, Waleed Younis, Tobias Seifert, Gunnar Nitsche

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Abstract

Techniques are described for crest factor reduction in power amplifier circuits. For example, crest factor reduction can keep the peak signal level of a signal for transmission to below a peak threshold level associated with a power amplifier in the transmission path. The signal is received by the crest factor reduction system and clipped in accordance with the peak threshold level. Edge smoothing is then applied to the clipped signal to reduce out-of-band emissions. The edge smoothing is implemented by a moving average filter, such as a time-domain box filter. In some embodiments, a maximum operation or minimum operation is used to prevent signal peak regrowth after the filtering. Some embodiments also include various iteration loops to further improve crest factor reduction.

Claims13

Dependent claims

A crest factor reduction system comprising:

an input node to receive an input data signal;
an output node to output an output data signal;
a clipper subsystem to generate, responsive to receiving a clipper input signal, a clipper output signal that is a clipped portion of the clipper input signal that exceeds a threshold peak level, the clipper subsystem having at least a first clipper mode in which the clipper subsystem is coupled with the input node, such that the clipper input signal is the input data signal;
a filter subsystem to generate, responsive to receiving a filter input signal, a filter output signal that is a function of an average of the filter input signal over a moving time window, the filter subsystem having at least a first filter mode in which the filter subsystem is coupled with the clipper subsystem, such that the filter input signal is the clipper output signal, the filter subsystem comprising:
a moving average filter to generate a moving average signal that is the average of the clipped portion of the filter input signal over the moving time window;
and
a maximum operation subsystem to receive the moving average signal and the filter input signal, and to generate the filter output signal by computing a maximum of the moving average signal with respect to the clipper output signal;
and
an output signal generator to generate the output data signal at the output node by subtracting the filter output signal from the input data signal.

6 more elements

A method for crest factor reduction comprising:

receiving an input data signal;
clipping the input data signal with respect to a threshold peak level to obtain a clipped portion of the input data signal that exceeds the threshold peak level;
generating a filter output signal by:
filtering the clipped portion of the input data signal by a moving average filter to generate a moving average signal that is the average of the clipped portion of the input data signal over the moving time window;
and
generating the filter output signal by computing a maximum of the moving average signal with respect to the clipped portion of the input data signal;
and
generating an output data signal by subtracting the filter output signal from the input data signal.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/057,822Filed 8 Aug 2018
Published: US 2020/0052656 A113 Feb 2020
Granted: 17 Mar 2020
Term ends: Not estimatedThe source records don’t support an estimate.

Classification15 codes

H04L 27/2623
Peak power aspects: reduction thereof by clipping
H03F 1/32
Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements: modifications of…
H03F 3/245
Of transmitter output stages: with semiconductor devices only
H04L 27/2626
Multicarrier modulation systems: arrangements specific to the transmitter only