Opto-electronic Oscillator Triple-Loop Architecture
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Solution Overview
Problem
Existing oscillator circuits face challenges in achieving ultra-low phase noise and ultra-stability of frequency, particularly in applications like radar and millimeter-wave integrated circuits, where high frequency signals are required.
Innovation Solution
A scalable differential triple-loop architecture is developed, incorporating electronic, opto-electronic, and purely optical loops that are injection locked together, enhancing RF oscillation stability and immunity to noise. This architecture includes a differential oscillator with an opto-electronic circuit loop, an optical loop, and an electrical feedback loop, featuring a transistor laser and injection-locked optical amplifier, which can be cascaded to achieve reduced RF phase noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional oscillator circuits are used, then circuit simplicity is maintained, but phase noise performance deteriorates
Solution Approach 1:
The oscillator circuit is divided into multiple functional modules: a resonant circuit module providing frequency determination, a modulation module converting electrical signals to optical signals, an optical delay line module providing time delay, and a detection module converting optical signals back to electrical signals. Each module performs a specific function, allowing the complex phase noise reduction mechanism to be implemented through coordinated simple components rather than a monolithic complex circuit
Solution Approach 2:
An optical signal serves as an intermediary carrier between the electrical signal at the resonant circuit and the feedback signal. The electrical signal modulates the optical signal in the modulation module, the optical signal travels through the delay line, and then converts back to electrical signal in the detection module. This optical intermediary enables the implementation of a triple-loop feedback structure that would be difficult to realize directly in the electrical domain, thereby reducing phase noise while managing circuit complexity
2Stability of the object's composition
If conventional oscillator circuits are used, then circuit structure is simple, but frequency stability deteriorates
Solution Approach 1:
The patent implements a triple-loop feedback structure where the output signal is fed back to the input through three distinct paths: an electrical feedback path, an opto-electronic feedback path with modulation and detection, and an optical feedback path with delay line. Each feedback loop provides phase correction and stabilizes the oscillation frequency. The combined effect of three feedback loops enhances frequency stability significantly compared to conventional single-loop oscillators, while the modular structure manages the complexity through functional decomposition
Solution Approach 2:
The patent transitions from a purely electrical domain to include optical domain components. By introducing optical signals, optical modulation, and optical detection, the system adds a new dimension to the feedback mechanism. This opto-electronic dimension provides additional degrees of freedom for controlling frequency stability through the optical delay line and optical resonator, enabling enhanced stability performance without being constrained by conventional electrical circuit limitations
3Object-affected harmful factors
If conventional oscillator circuits are used, then noise immunity is limited, but circuit design remains simple
Solution Approach 1:
The patent replaces conventional electrical signal processing with opto-electronic signal processing. By converting electrical signals to optical signals for transmission and processing, then converting back to electrical signals, the system exploits the advantages of optical signals (higher frequency, better noise immunity, lower interference) to improve performance. The differential pair structure further enhances noise immunity by rejecting common-mode noise, while the modular opto-electronic design manages the increased design complexity through functional separation
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
The solution significantly reduces RF phase noise and achieves ultra-low phase noise performance, making it suitable for high-frequency applications with improved stability and noise immunity, and is scalable for on-chip integration.
Implementation Method 1
an optical modulator that receives a first electrical signal and produces an optical output signal
Implementation Method 2
an optical resonator... increases the equivalent round trip delay of the optical signal in the loop, increasing the total Q
Implementation Method 3
a photodetector circuit optically coupled with said optical resonator
Implementation Method 4
a phase shifter coupled with said photodetector circuit for producing a phase shifted output signal
Data Source
AI summary
An opto-electronic oscillator circuit, including: an opto-electronic circuit loop including an optical modulator that receives a first electrical signal and produces an optical output signal coupled with an optical resonator, a photodetector circuit optically coupled with the optical resonator, and a phase shifter coupled with the photodetector circuit for producing a phase shifted output signal that is fed back as the first electrical signal; an optical loop comprising the optical coupling of the optical resonator with the photodetector; and an electrical feedback circuit loop for coupling the first electrical signal with the photodetector circuit.