Multistage Adaptive Equalizer for Low-Voltage CMOS Channels
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Solution Overview
Problem
Current adaptive equalizers require near-perfect tunable filters and high power supply voltages, limiting their implementation to only a few filter types and making them unsuitable for low-voltage operation and small chip areas, especially in CMOS technology.
Innovation Solution
The adaptive equalizer employs a plurality of adaptive amplification compensation stages with tuning parameters that can have binary or intermediate values, allowing for non-linear signal filtering behavior dependent on signal input, and operates at lower voltages by using transistors or capacitors with signal-amplitude-dependent resistive or capacitive values, enabling partial compensation with limited power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If near-perfect tunable filters are used to achieve ideal compensation, then equalization performance is improved, but device complexity and power supply voltage requirements increase
Solution Approach 1:
The equalizer is divided into multiple amplification stages, each with its own tuning parameter. Instead of using a single complex filter, the patent segments the compensation function across several simpler stages that can be independently adjusted, reducing overall device complexity while maintaining equalization performance.
Solution Approach 2:
The patent introduces dynamic tuning parameters that can be adjusted in real-time to adapt to different signal conditions. Each stage has tuning parameters that can vary between binary and intermediate values, allowing the system to dynamically optimize performance without requiring fixed complex filter structures.
2Reliability
If high power supply voltage is used to operate traditional adaptive equalizers, then filter performance is improved, but power consumption increases
Solution Approach 1:
The patent changes the operating parameters of the amplification stages by introducing intermediate tuning parameter values between binary states. This allows the stages to operate at lower voltages while still achieving effective compensation, as the intermediate values enable fine-grained control without requiring high voltage headroom.
Solution Approach 2:
Instead of requiring full compensation at each stage with high voltage, the patent applies partial compensation across multiple stages. Each stage contributes partially to the overall equalization, allowing the system to achieve the same result with lower individual stage voltages and reduced total power consumption.
3Ease of manufacture
If binary tuning parameters are used for simplicity, then circuit implementation is simplified, but equalization precision is reduced
Solution Approach 1:
The tuning parameters are made dynamic, allowing them to transition between binary and intermediate values based on signal conditions. This dynamic approach maintains the simplicity of binary control when possible while introducing intermediate values only when needed for enhanced precision, balancing implementation ease with equalization accuracy.
Solution Approach 2:
The equalization function is segmented across multiple stages, each with its own tuning parameter. This segmentation allows each stage to operate with simpler binary control while the cumulative effect of multiple stages achieves high overall precision, as each stage contributes a portion of the total equalization precision.
4Reliability
If multiple amplification stages are used to achieve better compensation, then equalization effectiveness is improved, but chip area increases
Solution Approach 1:
The patent merges multiple amplification stages into a compact multi-stage architecture where stages share common control structures and tuning mechanisms. This merging reduces the overall chip area compared to implementing separate independent filters, while still maintaining the benefits of multiple stages for effective equalization.
Solution Approach 2:
Each amplification stage is designed with multi-functionality, serving both as an amplifier and as a tunable filter element. The stages use shared control logic and tuning parameter generation circuits, allowing them to perform multiple functions with a smaller total area than dedicated single-function circuits would require.
Data Source
AI summary
The present invention is related to an adaptive equalizer comprising multiple tuning circuits that generate tuning signals. Each tuning signal can typically induce higher frequency gain up to a limited level, e.g. +5 dB, at the upper data frequency for compensation of high frequency losses in the connected transmission channel. Several tuning signals can tune one adaptive amplifying compensation stage. In its adaptive amplifying compensation stage the tuning signal can generate through its tuning function, non-linear small-signal and large-signal transfer behavior. However, by limiting the amount of higher frequency gain to maximum +8 dB per tuning function, and by having only one tuning function active at a time the resulting deterministic fitter remains tolerable. Several adaptive amplifying compensation stages introducing non-linear effects in the compensation behavior and their tuning functions are disclosed. Especially at low power supply voltage the merits of the present invention become apparent.