Photonic ADC Optical Hybrid for High-Power RF Digitization
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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 without attenuating weak signals below the noise floor.
Innovation Solution
The development of photonic ADCs using optical techniques, specifically an electro-optic modulator to encode RF signals onto optical phases, combined with noise cancellation and calibration algorithms, enables the creation of a high dynamic range ADC system that can digitize high-power electronic signals through unlimited optical phase wrapping and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic ADCs are used to measure signals, then noise performance is good, but the maximum voltage handling capability is limited due to physical damage in CMOS transistors
Solution Approach 1:
The patent replaces the electronic CMOS transistor-based ADC with a photonic ADC that uses optical components (electro-optic modulator, optical hybrid, photodetectors) to perform the analog-to-digital conversion. This substitution eliminates the physical damage issues inherent in electronic transistors when exposed to strong signals, while maintaining good noise performance through the optical measurement process.
Solution Approach 2:
The patent introduces an optical intermediary (light) between the RF signal and the digitization process. The RF signal modulates the optical carrier in the electro-optic modulator, and the optical signal is then processed through the optical hybrid and detected by photodetectors. This intermediary allows the system to handle high-power RF signals without the physical limitations of direct electronic processing.
2Object-affected harmful factors
If strong signals are attenuated below the ADC threshold, then the maximum voltage handling is improved, but weak signal characteristics are buried below the ADC noise floor
Solution Approach 1:
The patent segments the measurement process into two distinct channels: a main channel that handles strong signals through optical phase encoding with unlimited dynamic range, and a reference channel that captures weak signal characteristics without attenuation. This segmentation allows simultaneous accurate measurement of both strong and weak signals within the same system.
Solution Approach 2:
The patent transitions from a single-dimensional electronic voltage measurement to a multi-dimensional optical measurement space. By encoding signals in the optical phase domain and using multiple photodetector channels, the system creates additional measurement dimensions that allow simultaneous capture of both strong and weak signal characteristics without the trade-off present in single-channel electronic ADCs.
3Device complexity
If a single ADC is used to measure the entire voltage range, then device complexity is reduced, but the dynamic range is limited by the ADC's maximum voltage threshold
Solution Approach 1:
The patent creates a universal photonic ADC system that can handle the entire voltage range of RF signals through a single integrated device. The optical encoding mechanism provides unlimited dynamic range capability, allowing the same device to simultaneously measure both weak and strong signals without requiring multiple specialized ADCs or signal attenuation stages.
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 allows for accurate digitization of high-power signals across an extremely large dynamic range, reducing noise and calibration errors, and enabling the recording of the entire voltage range on a single device with low noise and high signal acceptance.
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.