Analog-Assisted Feed-Forward Equalizer for Low-Latency ISI Reduction
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Solution Overview
Problem
Conventional digital feed-forward equalizers suffer from high latency, increased power consumption, and area consumption due to the use of digital logic for arithmetic operations, which limits the maximum bandwidth and introduces signal-to-noise ratio degradation.
Innovation Solution
Analog-assisted feed-forward equalizers perform multiplication and addition operations in the analog domain using digital-to-analog converters and charge element DACs, reducing latency and consumption by processing some cursors in the analog domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital logic is used for arithmetic operations in feed-forward equalizers, then computational accuracy is improved, but latency increases and bandwidth is limited
Solution Approach 1:
The patent replaces digital logic arithmetic operations with analog circuit operations. Specifically, digital-to-analog converters (DACs) convert digital cursor values to analog currents, which are then summed by analog adders to produce the equalized signal. This substitution of digital computation with analog processing eliminates the latency inherent in digital arithmetic operations while maintaining computational accuracy through precise analog circuit design.
2Measurement precision
If digital logic is used for arithmetic operations in feed-forward equalizers, then computational accuracy is improved, but power consumption increases
Solution Approach 1:
The patent substitutes power-hungry digital logic arithmetic operations with more energy-efficient analog circuit operations. The analog implementation uses DACs to generate currents proportional to cursor values, and analog adders to sum these currents. This approach significantly reduces power consumption compared to digital multiplication and addition operations while preserving computational accuracy through careful analog circuit design and calibration.
3Measurement precision
If digital logic is used for arithmetic operations in feed-forward equalizers, then computational accuracy is improved, but area consumption increases
Solution Approach 1:
The patent replaces area-intensive digital logic circuits with more compact analog circuits. The analog implementation requires only DACs and current summing circuits, which occupy significantly less silicon area than the multiple multipliers, adders, and control logic required for digital arithmetic operations. This area reduction is achieved while maintaining computational accuracy through precise analog circuit design.
4Loss of time
If analog operations are used in feed-forward equalizers, then latency is reduced and bandwidth is improved, but signal-to-noise ratio degradation occurs
Solution Approach 1:
The patent uses analog operations to achieve low latency and high bandwidth while mitigating noise through careful circuit design. The analog adders sum currents directly without conversion delays, enabling real-time processing at high speeds. Noise is managed through precision analog circuit design, proper impedance matching, and calibration techniques that minimize the impact of thermal noise and other analog disturbances on the signal-to-noise ratio.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves reduced latency, power consumption, and area usage while maintaining signal integrity by performing arithmetic operations in parallel, thereby improving bandwidth and reducing inter-symbol interference.
Implementation Method 1
a first charge element digital-to-analog converter (DAC) with a first output, the first charge element DAC comprising a first plurality of charge storage elements, the first charge element DAC being configured to: store first samples of charge based on respective first portions of a digital input signal; and generate a first analog output signal proportional to the first portions of the digital input signal and based on the first samples of charge
Data Source
AI summary
The techniques described herein relate to analog-assisted feed-forward equalizers. An example apparatus includes a first charge element digital-to-analog converter (DAC) including a first plurality of charge storage elements configured to store first samples of charge based on respective first portions of a digital input signal, and generate, based on the first samples, a first analog output signal proportional to the first portions. The apparatus further includes a second charge element DAC coupled to the first charge element DAC and including a second plurality of charge storage elements configured to store second samples of charge based on respective second portions of the digital input signal, and generate, based on the second samples, a second analog output signal proportional to the second portions, and wherein the coupling of the first and second outputs generates a third analog output signal based on a combination of the first and second analog output signals.