Transmitter Equalizer Tuning via Receiver Gradient
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Solution Overview
Problem
High-speed data transmission over low-FOM hardware platforms like FR4 Printed Circuit Boards faces severe inter-symbol interference due to high-loss, non-linear, and reflective transmission channels, leading to signal degradation and errors.
Innovation Solution
A circuit with a receiver, monitor, and controller adjusts the transmitter equalizer tap values based on measured signal properties and figure of merit (FOM) to optimize signal transmission, using a gradient steepest ascent algorithm and FOM cache for improved convergence and repeatability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed data transmission is implemented over low-FOM hardware platforms, then data throughput increases, but inter-symbol interference and signal degradation worsen due to high-loss and non-linear transmission channels
Solution Approach 1:
The patent implements a feedback mechanism where the receiver measures the figure of merit (FOM) of the received signal and sends this information back to the transmitter. The transmitter then adjusts its equalizer tap values based on this feedback to optimize signal quality. This closed-loop feedback system enables continuous adaptation to channel conditions, resolving the contradiction between high data throughput and signal quality by dynamically compensating for transmission impairments.
Solution Approach 2:
The patent changes the parameters of the transmitter equalizer (specifically the tap values) to optimize signal transmission. By adjusting the equalizer coefficients based on measured channel characteristics and FOM feedback, the system adapts the transmission parameters to compensate for high-loss and non-linear effects, thereby maintaining signal quality at high data rates.
2Reliability
If transmitter equalizer tap values are adjusted to optimize signal transmission, then signal-to-noise ratio improves, but system complexity increases due to the need for monitoring and control mechanisms
Solution Approach 1:
The patent integrates multiple functions into the existing transmitter and receiver structures. The equalizer adjustment mechanism leverages existing components (transmitter equalizer, receiver FOM measurement) and adds a control loop that reuses these components for both data transmission and optimization purposes. This multi-functional approach minimizes additional hardware complexity while achieving SNR improvement.
3Measurement precision
If the controller compares FOM against multiple previous FOMs to determine differential, then tuning accuracy improves, but processing time increases
Solution Approach 1:
The patent uses a weighted comparison of FOM values where recent measurements are given higher weight than older ones. This partial action approach (focusing on the most relevant recent history rather than all possible historical data) achieves sufficient tuning accuracy while limiting the processing burden. The system processes only the necessary subset of historical FOM data required for effective gradient calculation.
Data Source
AI summary
A controller operates to adjust a transmitter to optimize transmission of a communications signal. The controller measures properties of a signal received from a transmitter, and generates a figure of merit (FOM) for the signal. The FOM is compared against a record of previous FOMs and corresponding previous transmitter tap values, the transmitter tap value indicating settings of a transmitter equalizer of the transmitter during transmission of the signal. A differential between the FOM and a plurality of the previous FOMs is determined, and, in response to the differential being positive, a subsequent tap value is selected from a subset of potential tap values. The subsequent tap value is sent to the transmitter for adjustment of the transmitter equalizer.