Photonic ADC Pulse Broadening for Low-Complexity RF Sampling
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Solution Overview
Problem
Existing photonic analog-to-digital converters face challenges with high cost, complexity, and power consumption due to the need for multiple electronic components and complex circuitry, particularly when handling short-optical-pulse samples, which compromises signal integrity and bandwidth.
Innovation Solution
The photonically-sampled, electronically-quantized analog-to-digital converter system employs a single-channel normalization scheme, passive detector-to-ADC interfaces, subtraction before ADCs, and post-modulator dispersion to reduce component count and power consumption while maintaining signal integrity, using wavelength interleaving and routing to simplify optical pulse demultiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple electronic components and complex circuitry are used to handle short-optical-pulse samples, then signal integrity and bandwidth are maintained, but cost, complexity, and power consumption increase significantly
Solution Approach 1:
The patent replaces complex electronic signal processing circuits with optical domain processing. Specifically, optical delay lines, optical switches, and optical correlators are used to perform functions that would otherwise require complex electronic timing and signal processing, thereby reducing electronic component count and power consumption while maintaining signal integrity
Solution Approach 2:
The patent introduces an optical buffer as an intermediary component between the photonic sampler and the electronic ADC. This optical buffer stores and manages short-optical-pulse samples without requiring complex electronic timing circuits, simplifying the overall system architecture while maintaining signal fidelity
2Reliability
If multiple electronic components and complex circuitry are used to handle short-optical-pulse samples, then signal integrity and bandwidth are maintained, but power consumption increases significantly
Solution Approach 1:
The patent substitutes high-power electronic signal processing circuits with low-power optical processing components. Optical switches and delay lines consume significantly less power than their electronic counterparts while maintaining the same signal processing functions, directly addressing the power consumption issue
3Speed
If photonic sampling is used, then timing jitter is reduced and bandwidth is increased, but system cost and complexity increase
Solution Approach 1:
The patent uses optical buffering to create temporal copies of short-optical-pulse samples, allowing them to be processed at a slower, more manageable rate. This copying mechanism preserves the high-speed sampling capability while reducing the complexity of subsequent electronic processing stages
Solution Approach 2:
The patent performs preliminary optical processing of samples before they reach the electronic ADC. By pre-processing signals in the optical domain (including delay, switching, and correlation), the system reduces the burden on electronic components, thereby reducing overall system complexity while maintaining high bandwidth performance
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 significantly reduces the number of electronic components and power consumption while achieving noise cancellation, linearization, and AM sideband suppression, improving signal integrity and bandwidth without compromising performance.
Implementation Method 1
A pulsed laser provides a high-speed, low-jitter pulse train to a modulator. The modulator imposes an RF modulation signal applied to an input of the modulator onto the sampling pulses generated by the pulsed laser to generate an optically sampled signal.
Implementation Method 2
The output of the modulator is coupled to an input of an optical pulse demultiplexer having a dispersive optical element that increases a width of the sampling pulses.
Data Source
AI summary
A photonically-sampled electronically-quantized analog-to-digital converter generates an optical signal comprising a series of optical pulses. The optical signal is split into a first and a second optical path. The split optical signal is detected in the first path and then the detected optical signal is converted to a reference digital signal. The split optical signal in the second path is modulated with an input RF signal and a plurality of demultiplexed RF-modulated optically-sampled signals is generated from the modulated optical signal. The plurality of demultiplexed RF-modulated optically-sampled signals is then pulse broadened, detected, and converted to a plurality of sampled-RF digital signals. The reference digital signal and the plurality of sampled-RF digital signals are digital signal processed to generate a digital representation of the input RF signal.