OOB Signal Detector Circuit for DC Rejection and AC Sampling
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Solution Overview
Problem
Existing out-of-band signal detection methods face challenges in accurately extracting and amplifying the modulated AC portion of electrical signals, which can be overwhelmed by the higher power DC portion, leading to diminished ADC resolution and reduced signal quality.
Innovation Solution
The method involves using a current to voltage processing circuit with multiple current mirror circuits to extract the AC portion, applying a gain to center the signal power within a specific range, and sampling to generate digital samples representing the modulated out-of-band data, ensuring the ADC operates within its optimal power range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the DC portion of the electrical signal is present during ADC conversion, then the ADC operates with reduced resolution for the AC portion, but the signal quality and measurement precision of the modulated out-of-band data deteriorate
Solution Approach 1:
The electrical signal is segmented into two separate processing paths: one for the DC portion and one for the AC portion. The current-to-voltage processing circuit with multiple current mirror circuits separates these components, allowing the ADC to convert only the AC portion at full resolution while the DC portion is processed independently and combined later, eliminating the resolution degradation caused by the high-power DC component.
Solution Approach 2:
The AC portion containing the modulated out-of-band data is extracted from the combined electrical signal using the current mirror circuit configuration. This extraction isolates the low-power modulated signal from the high-power DC portion, enabling the ADC to focus its dynamic range on the AC portion and achieve full measurement precision without being overwhelmed by the DC component.
2Power
If the full electrical signal including both AC and DC portions is amplified, then the signal power increases, but the ADC resolution for the AC portion decreases due to the higher dynamic range requirement
Solution Approach 1:
The signal processing is segmented into separate DC and AC paths. The AC portion is amplified independently with appropriate gain to achieve the desired signal power level for ADC conversion, while the DC portion is processed separately. This segmentation allows the amplifier to optimize its gain for the AC portion without being constrained by the much larger DC component, thereby maintaining ADC resolution.
Solution Approach 2:
The current mirror circuit acts as an intermediary that separates the DC and AC components before amplification. This intermediary structure enables independent gain control for the AC portion, allowing the amplifier to boost the low-power modulated signal to the optimal level for ADC conversion without being limited by the high-power DC component that would otherwise require much higher amplification.
3Device complexity
If a single amplifier handles both DC and AC portions, then the circuit complexity is reduced, but the ability to independently control gain for the AC portion is lost
Solution Approach 1:
The amplifier function is segmented into separate DC and AC amplification paths. The AC amplifier can be independently configured with specific gain settings optimized for the modulated out-of-band data, while the DC path has its own processing. This segmentation provides the adaptability and independent gain control needed for optimal AC signal processing, with the added benefit that each path can be optimized independently rather than requiring a single complex amplifier to handle both.
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
This approach effectively isolates and amplifies the AC portion, improving signal quality and ADC resolution, enabling accurate demodulation of out-of-band data without being affected by the DC portion's power level.
Implementation Method 1
a photodiode including an anode and a cathode. The photodiode may be configured to receive an optical in-band signal and an optical out-of-band signal from an optical cable and to generate an electrical signal based on the out-of-band optical signal
Data Source
AI summary
An out-of-band (OOB) signal detector is disclosed. The OOB signal detector may include a first node configured to receive an alternating current (AC) portion and a direct current (DC) portion of an electrical signal. The AC portion may include modulated OOB data carried by the electrical signal. The OOB signal detector may also include a current to voltage processing circuit configured to extract the AC portion of the electrical signal. The OOB signal detector may additionally include a limiting amplifier circuit configured to receive the extracted AC portion and to generate an amplified signal based on the extracted AC portion. The OOB signal detector may further include an analog-to-digital convertor circuit configured to sample the amplified signal and to generate a digital sample that represents the modulated OOB data.