US 11,855,702 B2
Circuit for multi-path interference mitigation in an optical communication system
Benjamin P. Smith, Ottawa (CA); Jamal Riani, Fremont, CA (US); Sudeep Bhoja, San Jose, CA (US); Arash Farhoodfar, Santa Clara, CA (US); and Vipul Bhatt, Los Altos, CA (US)
Assigned to MARVELL ASIA PTE LTD, Singapore (SG)
Filed by Marvell Asia Pte., Ltd., Singapore (SG)
Filed on Feb. 17, 2022, as Appl. No. 17/674,234.
Application 17/674,234 is a continuation of application No. 16/951,653, filed on Nov. 18, 2020, granted, now 11,258,518, issued on Feb. 22, 2022.
Application 16/951,653 is a continuation of application No. 16/790,463, filed on Feb. 13, 2020, granted, now 10,880,015, issued on Dec. 29, 2020.
Application 16/790,463 is a continuation of application No. 16/259,760, filed on Jan. 28, 2019, granted, now 10,601,518, issued on Mar. 24, 2020.
Application 16/259,760 is a continuation of application No. 15/836,603, filed on Dec. 8, 2017, granted, now 10,236,994, issued on Mar. 19, 2019.
Application 15/836,603 is a continuation of application No. 15/040,812, filed on Feb. 10, 2016, granted, now 9,876,581, issued on Jan. 23, 2018.
Prior Publication US 2022/0173814 A1, Jun. 2, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. H04B 10/69 (2013.01); H04B 10/58 (2013.01); H04B 10/2507 (2013.01); H04B 10/54 (2013.01); H04B 10/516 (2013.01); H04B 10/00 (2013.01)
CPC H04B 10/58 (2013.01) [H04B 10/00 (2013.01); H04B 10/2507 (2013.01); H04B 10/25073 (2013.01); H04B 10/5161 (2013.01); H04B 10/541 (2013.01); H04B 10/697 (2013.01); H04B 10/6971 (2013.01)] 10 Claims
OG exemplary drawing
 
1. An optical receiver comprising:
a receive circuit configured to receive an optical signal comprising a transmitted optical signal component and a reflected component and to convert the optical signal to a converted electrical signal, the reflected component including one or more reflections of the transmitted optical signal due to multipath interference (MPI) in a transmit path of the optical signal; and
an MPI mitigation circuit coupled to the receive circuit, the MPI mitigation circuit comprising feedforward circuitry that is configured to process the converted electrical signal to mitigate in the converted electrical signal a converted electrical signal component corresponding to the reflected component of the received optical signal and to generate an MPI-mitigated signal based on the processed converted electrical signal, wherein the feedforward circuitry comprises:
an error generator configured to estimate a power level of the optical signal from samples of the converted electrical signal and to generate an error signal;
a filter configured to filter the error signal and to output estimates of MPI in the samples; and
a combiner configured to combine the estimates of PI with the respective samples to generate the MPI-mitigated signal;
wherein the optical signal is modulated using pulse amplitude modulation (PAM) and wherein the combiner comprises a subtractor configured to:
generate weighted estimates of MPI by multiplying the estimates of MPI from the filter by PAM levels estimated from the respective samples; and
subtract the weighted estimates of MPI from the respective samples to generate the MPI-mitigated signal; and
wherein the MPI mitigation circuit is configured to generate estimates of MPI or samples of the converted electrical signal, the optical receiver further comprising:
an estimator coupled to the receive circuit and configured to estimate one or more interference components in the converted electrical signal that are generated by electrical reflections in portions of the receive circuit in the optical receiver and portions of electrical circuitry used in a transmitter for transmitting the optical signal;
wherein the combiner configured to combine the estimates of MPI generated by the MPI mitigation circuit and the estimates of the interference components generated by the estimator with the respective samples of the converted electrical signal to generate interference mitigated samples in which MPI caused by the reflections of the transmitted optical signal and the interference components generated by the electrical reflections are mitigated.