VGA-Specific Equalization in Network Transceivers With Interleaved ADCs
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Solution Overview
Problem
Conventional network transceivers face challenges in achieving high data transmission rates due to physical limitations on the conversion rates of analog digital converters (ADCs), and using multiple variable gain amplifiers (VGAs) introduces gain and bandwidth mismatches.
Innovation Solution
A network transceiver device employs a fanout architecture with two VGAs feeding 64 interleaved ADCs, utilizing channel-specific and common equalization coefficients for feed-forward equalizers (FFEs) to adaptively equalize signals, addressing gain and bandwidth mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple variable gain amplifiers (VGAs) are used to increase data transmission capacity, then the data transmission rate is improved, but gain and bandwidth mismatches are introduced
Solution Approach 1:
The patent divides the signal processing into separate VGA-specific channels, with each channel having its own dedicated VGAs and ADCs. This segmentation allows independent optimization and equalization of each channel, preventing the gain and bandwidth mismatches that would occur in a shared channel architecture.
Solution Approach 2:
The patent applies channel-specific equalization coefficients to each VGA channel individually, rather than using a single set of coefficients for all channels. This local quality approach ensures that each channel's unique gain and bandwidth characteristics are compensated for, maintaining signal consistency across multiple parallel channels.
2Device complexity
If a single set of equalization coefficients is used for all VGA channels, then device complexity is reduced, but equalization precision deteriorates due to gain and bandwidth mismatches
Solution Approach 1:
The equalization coefficients are segmented into channel-specific subsets, with each subset tailored to the characteristics of its corresponding VGA channel. This segmentation maintains equalization precision by accounting for channel variations while keeping the overall system manageable through modular coefficient management.
Solution Approach 2:
The patent employs a unified equalization framework that can handle both common and channel-specific coefficients through a single FFE structure. This multi-functionality allows the system to apply different coefficient sets to different channels without requiring separate equalization hardware for each channel, thus managing complexity efficiently.
3Productivity
If individual ADC conversion rates are limited, then device complexity is reduced, but the overall data transmission rate is constrained
Solution Approach 1:
The patent divides the high-rate data stream into multiple parallel channels, each handled by a separate ADC operating at a lower, manageable conversion rate. This segmentation allows the system to achieve high overall throughput by aggregating the capacity of multiple slower ADCs rather than requiring a single high-speed ADC.
Solution Approach 2:
The patent transitions from a single-dimensional high-speed conversion approach to a multi-dimensional parallel processing architecture. By distributing the data transmission task across multiple ADCs operating in parallel, the system achieves high data rates through spatial distribution rather than temporal speed, effectively adding a dimensional aspect to the conversion process.
Data Source
AI summary
A network transceiver device is provided, including at least two variable gain amplifiers (VGAs), and at least two sets of analog digital converters (ADCs), each set including ADCs coupled to an output of one of the VGAs, the sets being arranged in VGA-specific channels. The device includes a plurality of feed-forward equalizers (FFEs), each FFE being coupled to receive an output of one of the ADCs in one of the VGA-specific channels. Each FFE is configured to adaptively equalize the output received from the ADCs utilizing a first equalization coefficient subset with coefficient values that are common to all FFEs, and a second equalization coefficient subset that is channel specific and that has a first set of coefficient values for a first VGA-specific channel and a second set of coefficient values for a second VGA-specific channel, the sets of coefficient values being computed independently.