Photonic ADC Phase Encoding for High-Dynamic-Range RF Signals
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Solution Overview
Problem
Electronic analog-to-digital converters (ADCs) face limitations in handling high dynamic range signals due to noise issues and physical damage from strong signals, which restrict their ability to measure signals across a wide voltage range effectively.
Innovation Solution
The development of photonic ADCs using optical techniques, including an electro-optic modulator to encode RF signals onto optical phases, with noise cancellation and calibration algorithms to achieve a high dynamic range by generating multiple phase-shifted optical outputs for precise digitization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic ADCs are used to measure signals, then noise performance is improved, but the ability to handle high power signals deteriorates due to physical damage in CMOS transistors
Solution Approach 1:
The patent replaces electronic ADC components (CMOS transistors) with optical components (electro-optic modulators, photodetectors) to perform analog-to-digital conversion. The optical system measures voltage signals by converting them to optical phase modulations, avoiding direct electrical contact with high-power signals that would damage electronic components. This substitution enables both high noise performance and high power handling capability.
2Object-affected harmful factors
If strong signals are attenuated below the ADC threshold, then the ADC can handle high power signals, but weak signal characteristics are buried below the ADC noise floor
Solution Approach 1:
The patent changes the measurement parameter from direct voltage measurement to optical phase measurement. By converting the voltage signal to an optical phase modulation and then measuring the phase difference, the system achieves a much larger effective measurement range. The optical phase wrapping technique allows the system to measure both weak and strong signals with high precision by unwrapping the phase information through calibration algorithms.
3Adaptability or versatility
If optical phase wrapping with noise cancellation algorithms is used, then dynamic range is improved, but system complexity increases
Solution Approach 1:
The patent implements feedback through calibration algorithms that measure and compensate for system imperfections. The system performs calibration by injecting known test signals and measuring the actual optical phase responses, then uses this information to correct subsequent measurements. This feedback mechanism enables the noise cancellation and phase unwrapping algorithms to achieve high dynamic range performance despite the inherent complexity of the optical measurement system.
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 enables the digitization of high-power electronic signals with a significantly increased dynamic range, reducing noise and physical damage limitations, allowing for accurate measurement across a wide voltage range.
Implementation Method 1
an electro-optic (EO) modulator coupled to an output of the polarization rotator. The EO modulator is configured to receive a radio frequency (RF) signal and to produce a phase modulated signal in accordance with the RF signal
Implementation Method 2
an optical hybrid configured to receive two optical signals from the polarizing beam splitter and to produce four optical outputs that are each phase shifted with respect to one another
Data Source
AI summary
Devices, methods for analog-to-digital converters (ADCs) that perform high-dynamic range measurements based on optical techniques are disclosed. In one example aspect, an optical encoder includes a polarization rotator configured to receive a train of optical pulses, and an electro-optic (EO) modulator coupled to an output of the polarization rotator. The EO modulator is configured to receive a radio frequency (RF) signal and to produce a phase modulated signal in accordance with the RF signal. The optical encoder also includes a polarizing beam splitter coupled to the output of the EO modulator; and an optical hybrid configured to receive two optical signals from the polarizing beam splitter and to produce four optical outputs that are each phase shifted with respect to one another.