Interleaved ADC Receiver with Adaptive Equalization for 10G Links
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Solution Overview
Problem
Implementing 10G optical communication systems over multi-mode fibers is challenging due to high dispersion and variability, requiring complex and expensive components like 10G ADCs, which are difficult to build and maintain, especially with existing materials and circuit designs.
Innovation Solution
A receiver and transceiver system featuring an interleaved ADC coupled with a multi-channel equalizer, using feedforward equalization and Viterbi decoding, along with adaptive algorithms like LMS, and incorporating open-loop residue amplifiers and lookup table calibration to compensate for channel impairments and non-linearity, allowing for independent or shared equalization of multiple channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 10G ADCs are used to achieve high-speed data transmission, then data rate is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides the high-speed ADC operation into multiple parallel lower-speed channels (e.g., 4 channels operating at 2.5 GS/s instead of 1 channel at 10 GS/s). Each channel processes a portion of the data stream, allowing the system to achieve 10G aggregate throughput while each individual ADC channel operates at a more manageable and less complex speed, thereby reducing per-channel complexity and manufacturing difficulty
Solution Approach 2:
The patent transitions from a single high-speed time domain approach to a multi-channel parallel architecture, effectively adding a spatial dimension (multiple channels) to the problem. This dimensional change allows the system to achieve high data rates through parallelism rather than through increasing the clock speed of a single ADC, thus avoiding the complexity associated with ultra-high-speed single-channel operation
2Productivity
If complex circuit designs are used to achieve high-speed operation, then data rate is improved, but cost increases
Solution Approach 1:
By segmenting the high-speed conversion into multiple parallel lower-speed channels, the patent enables the use of standard, off-the-shelf ADC components operating at moderate speeds rather than requiring custom-designed ultra-high-speed ADCs. This segmentation allows manufacturers to use proven, lower-cost technologies for each channel while achieving the aggregate 10G performance through parallel operation
Solution Approach 2:
The patent designs the multi-channel system with shared resources and common processing stages that can handle multiple channels simultaneously. This universal architecture allows the same circuit design to be replicated across channels, reducing overall system cost through economies of scale and standardized component usage rather than requiring unique complex circuits for each high-speed channel
3Productivity
If 10G ADCs are used to achieve high-speed data transmission, then data rate is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent divides the precision requirements across multiple parallel channels, where each channel operates at a lower speed (e.g., 2.5 GS/s) with correspondingly relaxed precision and timing requirements. The cumulative precision across all channels achieves the overall 10G performance without requiring any single channel to meet the extremely tight precision specifications that would be necessary for a monolithic 10G ADC
Solution Approach 2:
The patent changes the operating parameters of the ADC system by reducing the sampling rate of individual channels from 10 GS/s to lower rates (e.g., 2.5 GS/s). This parameter change fundamentally relaxes the precision requirements for timing jitter, aperture uncertainty, and quantization accuracy, as these parameters scale favorably with lower operating frequencies, thereby making manufacturing significantly more achievable
Data Source
AI summary
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 decorder, 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.