Optical ADC Architecture for High-Frequency Signal Digitization
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Solution Overview
Problem
Conventional analog-digital converters face limitations in resolution and sampling frequency, especially when dealing with high-frequency analog input signals, due to the resolution of downstream electronic converters and accuracy requirements.
Innovation Solution
An optical input stage is used to convert analog input signals into phase-modulated optical signals, which are then processed through a hybrid coupler and converted back to electrical signals using photodiodes, allowing for increased resolution and sampling frequency by distributing the signal across multiple parallel converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electronic analog-digital converters are used, then the device complexity is low, but the measurement precision and sampling frequency are limited
Solution Approach 1:
The converter is divided into multiple parallel electronic analog-digital converter units, each processing a portion of the optical signal spectrum. This segmentation allows the system to achieve higher overall resolution by combining the outputs of multiple lower-resolution converters, while each individual converter maintains relatively simple circuitry.
Solution Approach 2:
The patent transitions from purely electronic signal processing to an optoelectronic hybrid approach by introducing optical carriers and photodetectors. This dimensional change from electrical to optical domain enables higher bandwidth and sampling frequencies that cannot be achieved with conventional electronic converters alone.
2Measurement precision
If the sampling rate is increased to meet Nyquist Theorem requirements for high-frequency signals, then the measurement precision improves, but the device complexity and difficulty of detecting and measuring increase
Solution Approach 1:
The patent replaces the electronic time-base generation and signal sampling mechanism with an optical carrier-based sampling approach. The optical carrier's high frequency enables precise time-axis quantization without requiring complex electronic timing circuits, thereby improving quantization accuracy while reducing the difficulty of high-frequency measurement.
3Productivity
If optical carriers are used to increase bandwidth and sampling frequency, then the productivity increases, but the device complexity increases due to additional optical components
Solution Approach 1:
The optical carrier serves multiple functions simultaneously: it acts as the signal transmission medium, provides the sampling clock reference through its frequency, enables frequency multiplication for higher bandwidth, and facilitates parallel processing across multiple photodetector channels. This multi-functionality increases productivity while minimizing the addition of separate dedicated components.
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 reliable digitization of high-frequency analog signals with higher resolution and sampling frequency, overcoming the limitations of conventional converters by distributing the signal processing across multiple parallel converters.
Implementation Method 1
convert the analog input signal into a phase-modulated optical signal
Implementation Method 2
a plurality of output waveguides (122) configured to transfer the phase-modulated input signal into a plurality of output signals
Implementation Method 3
converting back to electrical signals using photodiodes
Data Source
AI summary
An analog-digital converter has an optical input stage configured to convert an analog input signal (S(t)) into a phase-modulated optical signal and to supply it to a hybrid coupler having a plurality of output waveguides, each being connected to at least one photodiode. The photodiodes are each connected to the input of an associated analog-digital converter via which an analog electrical input signal is convertible into a digital output signal. An output stage is configured to form the digital data stream at the output from the digital output signals of the analog-digital converter, and the output stage may be configured to select the output signal of the analog-digital converter which lies within a predefinable range of the amplitude and has a predefinable slope and/or is larger than a predefinable adjacent output signal.