High-speed receiver architecture

• US 9,531,475 B2
• Filed: 09/08/2014
• Issued: 12/27/2016
• Est. Priority Date: 10/03/2005
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: ClariPhy Communications Incorporated (Inphi Corporation)
• Inventors: Agazzi, Oscar Ernesto, Crivelli, Diego Ernesto, Carrer, Hugo Santiago, Hueda, Mario Rafael, Luna, German Cesar Augusto, Grace, Carl
• Primary Examiner(s): Corrielus, Jean B
• Application Number:
  US14/480,085
• Publication Number:
  US 20150098710A1
• Time in Patent Office: 841 Days
• US Class Current: 1/1
• CPC Class Codes: H03M 13/41 using the Viterbi algorithm or Viterbi processors
• CPC Class Codes: H04B 1/38 Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
• CPC Class Codes: H04B 10/25073 using spectral equalisation, e.g. spectral filtering
• CPC Class Codes: H04B 10/2941 using an equalising unit, e.g. a filter H04B10/296 takes precedence
• CPC Class Codes: H04B 10/40 Transceivers
• CPC Class Codes: H04B 10/5059 using a feed-forward signal generated by analysing the optical or electrical input
• CPC Class Codes: H04B 10/6971 using equalisation
• CPC Class Codes: H04B 2001/0441 with linearisation using feed-forward
• CPC Class Codes: H04B 2201/709772 Joint detection using feedforward
• CPC Class Codes: H04B 3/235 combined with adaptive equaliser
• CPC Class Codes: H04B 7/005 Control of transmission; Equalising
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04L 2025/03477 not time-recursive
• CPC Class Codes: H04L 2025/03617 Time recursive algorithms H04L2025/03643 takes precedence
• CPC Class Codes: H04L 25/0202 Channel estimation
• CPC Class Codes: H04L 25/025 using least-mean-square [LMS] method
• CPC Class Codes: H04L 25/03038 with a non-recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 25/03057 with a recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission

Abstract

A receiver (e.g., for a 10G fiber communications link) includes an interleaved ADC coupled to a multi-channel equalizer that can provide different equalization for different ADC channels within the interleaved ADC. That is, the multi-channel equalizer can compensate for channel-dependent impairments. In one approach, the multi-channel equalizer is a feedforward equalizer (FFE) coupled to a Viterbi decoder, for example a sliding block Viterbi decoder (SBVD); and the FFE and/or the channel estimator for the Viterbi decoder are adapted using the LMS algorithm.

Claims

1. A transceiver chip for communication over a fiber optic, the transceiver chip comprising:

a host interface for receiving digital data in electrical form, the received digital data in a host format;

a laser driver port for generating an electrical signal modulated by the received digital data in electrical form, the electrical signal suitable for driving a laser driver;

transmit path circuitry coupled between the host interface and the laser driver port;

an input port for receiving an electrical signal from a transimpedance amplifier, the received electrical signal modulated by data; and

receive path circuitry coupled between the input port and the host interface, the host interface further for transmitting digital data in electrical form, the transmitted digital data also in the host format, the receive path circuitry comprising;

an analog-to-digital converter to receive the electrical signal from the transimpedance amplifier via the input port, and to generate signal samples from the received electrical signal, the received electrical signal having combined non-Gaussian noise and Gaussian noise;

a feedforward equalizer coupled to receive the signal samples from the analog-to-digital converter, and to apply equalization based on a cumulative metric function to generate equalized samples, the cumulative metric function to compensate for the combined non-Gaussian noise and Gaussian noise in the received signal samples, wherein the cumulative metric function is approximated by M≈

Σ

_n[(ŷ

_n)^v−

(ŝ

_n)^v]² where M is the cumulative metric function, ŷ

_n represents a symbol at an output of the feedforward equalizer, ŝ

_n is a noise-free signal component of ŷ

_n, where 0<

v≦

1;

a decoder coupled to the output of the feedforward equalizer, the decoder determining detected symbols based on the equalized samples and a channel model; and

a channel estimator coupled to receive the output of the feedforward equalizer and an output of the decoder and generate the channel model and an error feedback signal to adaptively update coefficients of the feedforward equalizer based on the error feedback signal.

2. The transceiver chip of claim 1, where v is given by

3. The transceiver chip of claim 1, further comprising:

a transformation block to provide an approximate solution to (ŷ

_n)^v, wherein the transformation block implements a function LUT(ŷ

_n)=(ŷ

_n+y_min)^v when the sample ŷ

_n is in an interval between −

y_min and +y_min.

4. A receiver comprising:

an analog-to-digital converter that generates signal samples from a received signal having combined non-Gaussian noise and Gaussian noise;

a feedforward equalizer coupled to receive the signal samples from the analog-to-digital converter, and to apply equalization based on a cumulative metric function to generate equalized samples, the cumulative metric function to compensate for the combined non-Gaussian noise and Gaussian noise in the received signal samples, wherein the cumulative metric function is approximated by M≈

Σ

_n[(ŷ

_n)^v−

(ŝ

_n)^v]² where M is the cumulative metric function, ŷ

_n represents a symbol at an output of the feedforward equalizer, ŝ

_n is a noise-free signal component of ŷ

_n, where 0<

v≦

1;

a decoder coupled to the output of the feedforward equalizer, the decoder determining detected symbols based on the equalized samples and a channel model; and

a channel estimator coupled to receive the output of the feedforward equalizer and an output of the decoder and generate the channel model and an error feedback signal to adaptively update coefficients of the feedforward equalizer based on the error feedback signal.

5. The receiver of claim 4, where v is given by

6. The receiver of claim 4, further comprising:

a transformation block to provide an approximate solution to (ŷ

_n)^v, wherein the transformation block implements a function LUT(ŷ

_n)=(ŷ

_n+y_min)^v when the sample ŷ

_n is in an interval between −

y_min and +y_min.

7. The receiver of claim 4, further comprising:

a transformation block to provide an approximate solution to (ŷ

_n)^v, wherein the transformation block implements a function y^v≈

y^vref└

1+(v−

v_ref)log(y)+0.5(v−

v_ref)²(log(y))²┘

where V_ref is a tabulated reference.

8. The receiver of claim 4, further comprising:

a transformation block to provide an approximate solution to (ŷ

_n)^v, wherein the transformation block implements a function K<sup>−

1</sup>ŷ

^0.5+(v−

0.5)ŷ

where K is a constant.

9. The receiver of claim 4, where v is given by v=0.5 if M_2,1/M_2,0>

K_0.5 and by v=1, where K_0.5 is a programmable threshold level.

10. The receiver of claim 4, wherein the non-Gaussian noise comprises amplified spontaneous emission (ASE) noise.

11. A method for equalizing a received signal, the method comprising:

generating, by an analog-to-digital converter, signal samples from the received signal having combined non-Gaussian noise and Gaussian noise;

applying, by a feedforward equalizer, an equalization to the signal samples from the analog-to-digital converter based on a cumulative metric function to generate equalized samples, the cumulative metric function to compensate for the combined non-Gaussian noise and Gaussian noise in the received signal samples, wherein the cumulative metric function is approximated by M≈

Σ

_n[(ŷ

_n)^v−

(ŝ

_n)^v]² where M is the cumulative metric function, ŷ

_n represents a symbol at an output of the feedforward equalizer, ŝ

_n is a noise-free signal component of ŷ

_n, where 0<

v≦

1;

determining, by a decoder coupled to the output of the feedforward equalizer, detected symbols based on the equalized samples and a channel model; and

generating, by a channel estimator the channel model and an error feedback signal to adaptively update coefficients of the feedforward equalizer based on the error feedback signal.

12. The method of claim 11, where v is given by

13. The method of claim 11, further comprising:

providing an approximate solution to (ŷ

_n)^v, by implementing a function LUT(ŷ

_n)=(ŷ

_n+y_min)^v when the sample ŷ

_n is in an interval between −

y_min and +y_min.

14. The method of claim 11, further comprising:

providing an approximate solution to (ŷ

_n)^v, by implementing a function y^v≈

y^vref└

1+(v−

v_ref)log(y)+0.5(v−

v_ref)²(log(y))²┘

where v_ref is a tabulated reference.

15. The method of claim 11, further comprising:

providing an approximate solution to (ŷ

_n)^v, by implementing a function K<sup>−

1</sup>ŷ

^0.5+(v−

0.5)ŷ

where K is a constant.

16. The method of claim 11, where v is given by v=0.5 if M_2,1/M_2,0>

K_0.5 and by v=1, where K_0.5 is a programmable threshold level.

17. The method of claim 11, wherein the non-Gaussian noise comprises amplified spontaneous emission (ASE) noise.