TROSA Low-Pass Filter for DAC Aliasing Noise Suppression
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Solution Overview
Problem
In optical communication systems, high data and symbol rates lead to electrical signal interference, causing aliasing noise in analog signals and transmitted optical signals, which affects data integrity.
Innovation Solution
Incorporation of low pass filters in the electrical paths connecting DAC circuitry to optical blocks and transimpedance amplifiers (TIAs) with automatic gain control circuits (AGCs) to attenuate high-frequency noise components, reducing errors in transmitted and received data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high data and symbol rates are used to increase data-carrying capacity, then productivity is improved, but electrical signal interference causes aliasing noise that worsens signal quality
Solution Approach 1:
A low-pass filter is placed in the electrical path between the DAC circuit and the optical modulator to preemptively remove high-frequency aliasing noise components before they can interfere with the optical modulation process. This preliminary filtering action prevents the noise from affecting signal quality while allowing high data rates to maintain productivity.
2Productivity
If spectral spacing between optical signals is reduced to increase capacity, then productivity is improved, but signal interference increases which worsens reliability
Solution Approach 1:
The low-pass filter removes high-frequency components and aliasing noise before optical modulation, ensuring that closely spaced optical signals are modulated with cleaner baseband signals. This preliminary noise removal improves signal integrity and reduces inter-channel interference, enabling more reliable operation at higher spectral densities.
3Productivity
If DAC sampling rate is increased to support higher symbol rates, then productivity is improved, but electrical interference between digital signals worsens noise in analog outputs
Solution Approach 1:
The low-pass filter extracts and removes the harmful high-frequency aliasing noise components from the analog signal output of the DAC. By separating and eliminating these unwanted high-frequency components generated by the high-rate DAC, the filter preserves the useful baseband signal while removing the electrical interference that would otherwise degrade signal quality.
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
The low pass filters effectively suppress high-frequency noise, improving signal quality and reducing errors in both transmitted and received data by blocking or substantially attenuating unwanted frequency components.
Implementation Method 1
The electrical paths include a low pass filter to block high frequency components of the analog signal, thereby eliminating or substantially reducing noise in the analog signals.
Data Source
AI summary
Consistent with the present disclosure, low pass filters are provided in the electrical paths connecting digital to analog converter (DAC) circuitry to an optical block package (also referred to as a “gold box”). The low pass filter blocks or substantially attenuates high frequency noise components present in an analog signal output from the DAC, thereby reducing errors that might otherwise be present in the transmitted data.