Millimeter-Wave Signal Generation Through Optical Frequency Multiplication
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Solution Overview
Problem
Existing methods for generating millimeter-wave signals using phase-locked loops result in high phase noise due to up-conversion of electrical signals, leading to poor signal linearity and increased noise, necessitating a method to generate signals with low phase noise.
Innovation Solution
A system utilizing an optoelectronic oscillator to generate a single-frequency signal with low phase noise, followed by frequency multiplication in electrical and optical domains, and frequency mixing to produce a millimeter-wave signal with reduced phase noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If up-conversion is performed on electrical signals to generate millimeter-wave signals, then the signal frequency is increased, but phase noise increases
Solution Approach 1:
The patent replaces the traditional electrical up-conversion process with an optical domain approach. The baseband signal is first converted to optical domain using an electro-optic modulator, then frequency multiplication is performed optically, and finally converted back to electrical domain. This substitution of the operational domain (from electrical to optical and back) enables frequency multiplication without the phase noise accumulation that occurs in conventional electrical up-conversion processes.
Solution Approach 2:
The patent introduces an optical dimension to the signal processing workflow. Instead of performing frequency multiplication directly in the electrical domain, the signal is transferred to the optical domain where frequency multiplication can be performed without causing in-band aliasing. This dimensional transition allows the system to achieve millimeter-wave frequencies while maintaining low phase noise by utilizing the properties of optical signals.
2Speed
If frequency multiplication is performed on wideband signals in electrical domain, then the signal frequency is increased, but in-band aliasing occurs
Solution Approach 1:
The patent substitutes electrical domain frequency multiplication with optical domain frequency multiplication. By performing the frequency multiplication operation in the optical domain using optical frequency multiplication units, the system avoids the in-band aliasing problem that occurs when performing electrical frequency multiplication. The optical domain provides sufficient bandwidth headroom to accommodate the frequency multiplication without causing aliasing.
3Ease of manufacture
If traditional phase-locked loop methods are used to generate millimeter-wave signals, then the signal can be generated, but phase noise is high
Solution Approach 1:
The patent segments the signal generation process into distinct functional stages: baseband signal generation, optical domain frequency multiplication, and conversion to millimeter-wave frequencies. By separating these functions into independent modules (wideband signal generation unit, optical frequency multiplication unit, etc.), the system can optimize each stage to minimize phase noise while maintaining overall signal generation capability.
Solution Approach 2:
The patent introduces an optical carrier as an intermediary medium between the baseband signal and the final millimeter-wave output. The electro-optic modulator serves as an intermediary device that transfers the baseband signal to the optical domain, where frequency multiplication occurs without direct electrical signal interaction that would generate phase noise. This intermediary optical domain acts as a noise-isolating layer.
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 proposed method significantly reduces phase noise, improving signal-to-noise ratio and linearity, enabling higher detection performance and communication capacity in radar and communication systems.
Implementation Method 1
a second signal generation unit, configured to generate a first single-frequency signal, where the second signal generation unit is an optoelectronic oscillator
Implementation Method 2
an electro-optic modulator, configured to modulate the first wideband signal onto an optical carrier
Implementation Method 3
a frequency mixing unit, configured to perform frequency mixing on the second wideband signal and the second single-frequency signal to obtain a millimeter-wave signal
Data Source
AI summary
A system is provided and used in the radar field. The system includes: a wideband signal generation unit configured to generate a first wideband signal; a second signal generation unit configured to generate a first single-frequency signal; a first frequency multiplication unit configured to perform frequency multiplication on the first wideband signal in optical domain to obtain a second wideband signal; a second frequency multiplication unit configured to perform frequency multiplication on the first single-frequency signal to obtain a second single-frequency signal; and a frequency mixing unit configured to perform frequency mixing on the second wideband signal and the second single-frequency signal to obtain a millimeter-wave signal. In this application, frequency multiplication is performed on a single-frequency signal in electrical domain and on a wideband signal in optical domain, so that a millimeter-wave signal with low phase noise can be obtained.