Optical ADC Architecture for High-Frequency Signal Digitization
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Solution Overview
Problem
Conventional analog-to-digital converters face limitations in resolution and sampling frequency, especially at high frequencies, due to low amplitude resolution and time discretization errors, which restrict their ability to accurately digitize high-frequency signals.
Innovation Solution
An optical analog-to-digital converter is designed with an optical input stage that converts the analog signal into a phase-modulated optical signal using a local oscillator, which is then processed through a hybrid coupler and converted back to electrical signals by photodiodes, allowing for increased resolution and sampling frequency by using multiple parallel converters and a sample-and-hold element to maintain accuracy during rapid signal changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electronic analog-to-digital converters are used, then the device complexity is low, but the measurement precision and sampling frequency are limited especially at high frequencies
Solution Approach 1:
The patent replaces the conventional electronic analog-to-digital conversion system with an optical-based system. The electronic converter is substituted by an optical modulator that modulates an optical carrier signal with the analog input signal, followed by optical switching and detection. This substitution enables higher measurement precision and sampling frequencies by leveraging the advantages of optical systems over electronic systems at high frequencies.
Solution Approach 2:
The patent introduces an optical carrier signal as an intermediary between the analog input signal and the digital output. The analog signal modulates the optical carrier, which then serves as the medium for subsequent optical switching and detection processes. This intermediary enables the system to achieve higher precision and bandwidth than direct electronic conversion.
2Productivity
If the sampling frequency is increased to digitize high-frequency signals, then the bandwidth is improved, but time discretization errors increase reducing accuracy
Solution Approach 1:
The patent employs periodic optical carrier signals with well-defined timing intervals to enable precise time discretization. The optical switching operation occurs at regular intervals synchronized with the optical carrier, providing accurate time stamping of signal samples. This periodic action allows high sampling frequencies while maintaining time discretization accuracy through the inherent timing precision of the optical domain.
3Measurement precision
If optical analog-to-digital conversion is implemented, then the resolution and sampling frequency are improved, but the device complexity increases
Solution Approach 1:
The patent segments the analog-to-digital conversion process into distinct functional modules: optical modulation stage, optical switching stage, and optical detection stage. Each module performs a specific function, allowing independent optimization and simplifying the overall design. The hybrid coupler further segments the optical signal into multiple paths for parallel processing, achieving high resolution through modular architecture rather than monolithic complexity.
4Productivity
If multiple parallel converters are used to increase bandwidth, then the sampling frequency is improved, but the device complexity and cost increase
Solution Approach 1:
The patent merges multiple conversion functions into a single integrated optical system. Instead of using separate parallel electronic converters, the invention combines modulation, switching, and detection in one optical pathway. The hybrid coupler merges multiple optical signal paths into a unified detection scheme, achieving the equivalent of parallel processing with a single integrated device, thereby increasing bandwidth without proportionally increasing complexity.
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 signals with higher resolution and sampling frequency, overcoming the limitations of conventional converters by enhancing the resolution and bandwidth, and allowing for accurate processing of signals beyond 10 GHz.
Implementation Method 1
an optical input stage which is set up to convert the analog input signal into a phase modulated optical signal
Implementation Method 2
converted back to electrical signals by photodiodes
Data Source
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AI summary
The invention relates to an analogue-digital converter (5) having at least one input, to which at least one analogue input signal (S(t)) can be supplied, and at least one output (31), which is configured to output a digital data stream that represents the analogue input signal, wherein the analogue-digital converter has an optical input stage (1), which is designed to convert the analogue input signal (S(t)) into a phase-modulated optical signal and to feed the signal to a hybrid coupler (12) having a plurality of output waveguides (122), each connected to at least one photodiode (13a, 13b), the connection contacts of the photodiodes (13a, 13b) are each connected to the input of an associated analogue-digital converter (21a, 21b), with which converters an analogue electrical input signal can be converted into a digital electrical output signal and the output of the analogue-digital converters (21a, 21b) is connected to the inputs of an output stage (3), which is designed to form the digital data stream at the output (31) from the digital output signals of the analogue-digital converters (21a, 21b), wherein the output stage (3) is designed to select the output signal of the analogue-digital converter (21a) that lies inside a specifiable range of amplitude and has a specifiable slope and/or is greater than specifiable adjacent output signal. The invention further relates to a corresponding method for generating a digital data stream.