# US 12,763,805 B2 · Method and apparatus for crest factor reduction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,763,805 B2 - Document ID: US12763805B2 - Status: Granted - Kind: B2 - Application number: 18/147,720 - Filed: 2022-12-29 - Published: 2024-07-04 - Granted: 2026-10-13 - Earliest claimed: 2022-12-29 - Assignees: Intel Corporation - Applicants: Intel Corporation - Inventors: Kannan Rajamani; Sunitha Motipalli; Albert Molina; Joseph Othmer; Kameran Azadet - Web page: https://patentgrep.com/patent/US12763805B2 ## CPC - H04B 1/0475: {with means for limiting noise, interference or distortion (H04B1/0483 takes precedence)} - H04L 27/2623: {Reduction thereof by clipping} - H04B 2001/0408: {with power amplifiers} - H04B 2201/70706: with means for reducing the peak-to-average power ratio - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract An apparatus and method for performing crest factor reduction (CFR). A peak detection circuit detects peaks from input signal samples based on a first threshold. The first threshold is higher than a second threshold that is determined based on a target peak-to-average power ratio (PAPR). A gain computation circuit determines a gain factor for at least one detected peak. A scaled cancellation pulse generation circuit generates a scaled cancellation pulse for the at least one detected peak based on the gain factor. A combiner circuit combines the scaled cancellation pulse with the input signal samples to generate an output signal. A hard clipping circuit may compress the output signal based on the second threshold. The first threshold is set slightly higher than the second threshold. ## Claims ### Claim 1 An apparatus for performing crest factor reduction (CFR), comprising: a peak detection circuit configured to detect peaks from input signal samples based on a first threshold, wherein the first threshold is higher than a second threshold that is determined based on a target peak-to-average power ratio (PAPR); a gain computation circuit configured to determine a gain factor for at least one detected peak; a scaled cancellation pulse generation circuit configured to generate a scaled cancellation pulse for the at least one detected peak based on the gain factor; and a combiner circuit configured to combine the scaled cancellation pulse with the input signal samples to generate an output signal. ### Claim 2 (depends on 1) The apparatus of claim 1, further comprising: a hard clipping circuit configured to compress the output signal based on the second threshold. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the peak detection circuit is configured to group detected peaks into a plurality of clusters and select a cluster peak from each cluster, the gain computation circuit is configured to determine the gain factor for each cluster peak, and the scaled cancellation pulse generation circuit is configured to generate the scaled cancellation pulse for each cluster peak. ### Claim 4 (depends on 1) The apparatus of claim 1, further comprising: a memory for storing cancellation pulses, wherein the scaled cancellation pulse generation circuit is configured to obtain a cancellation pulse from the memory based on parameters of the input signal samples and generate the scaled cancellation pulse by multiplying the gain factor for the at least one detected peak with the cancellation pulse obtained from the memory. ### Claim 5 (depends on 4) The apparatus of claim 4, wherein the cancellation pulses stored in the memory are generated based on a transmission scheme of the input signal samples. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the scaled cancellation pulse is generated and combined with the input signal samples in one iteration. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the first threshold is 2-3% higher than the second threshold. ### Claim 8 (depends on 1) The apparatus of claim 1, further comprising an up-sampling circuit configured to up-sample the input signal samples, and the peak detection circuit is configured to detect the peaks from the up-sampled input signal samples based on the first threshold. ### Claim 9 (depends on 1) The apparatus of claim 1, further comprising: a digital-to-analog converter configured to convert the output signal to an analog signal; and a power amplifier configured to amplify the analog signal. ### Claim 10 A method for crest factor reduction (CFR), comprising: detecting peaks from input signal samples based on a first threshold, wherein the first threshold is higher than a second threshold that is determined based on a target peak-to-average power ratio (PAPR); determining a gain factor for at least one detected peak; generating a scaled cancellation pulse for the at least one detected peak based on the gain factor; and combining the scaled cancellation pulse with the input signal samples to generate an output signal. ### Claim 11 (depends on 10) The method of claim 10, further comprising: compressing the output signal based on the second threshold. ### Claim 12 (depends on 10) The method of claim 10, wherein the detected peaks are grouped into a plurality of clusters and a cluster peak is selected from each cluster, the gain factor is determined for each cluster peak, and the scaled cancellation pulse is generated for each cluster peak. ### Claim 13 (depends on 10) The method of claim 10, further comprising obtaining a pre-stored cancellation pulse from a memory based on parameters of the input signal samples, wherein the scaled cancellation pulse is generated by multiplying the gain factor for the at least one detected peak with the pre-stored cancellation pulse obtained from the memory. ### Claim 14 (depends on 13) The method of claim 13, wherein the pre-stored cancellation pulse is generated based on a transmission scheme of the input signal samples. ### Claim 15 (depends on 10) The method of claim 10, wherein the scaled cancellation pulse is generated and combined with the input signal samples in one iteration. ### Claim 16 (depends on 10) The method of claim 10, wherein the first threshold is 2-3% higher than the second threshold. ### Claim 17 (depends on 10) The method of claim 10, further comprising up-sampling the input signal samples, wherein the peaks are detected from the up-sampled input signal samples based on the first threshold. ### Claim 18 (depends on 10) A non-transitory computer-readable medium having instructions stored thereon that, when executed by processing circuitry, cause the processing circuitry to perform the method of claim 10.