Terahertz Transceiver Front-End With Ring Coupler Image Rejection
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Solution Overview
Problem
Existing terahertz solid-state high-speed communication system transceiver front-ends suffer from poor noise performance, low circuit integration, and weak image frequency rejection capability due to incomplete circuit architectures and manual assembly errors.
Innovation Solution
A hetero-integrated terahertz low-noise miniaturized image frequency rejection transceiver front-end is developed, utilizing a ring 135° 3 dB filter coupler and a double-layer circuit layout with quartz hetero-integrated subharmonic mixers to achieve low-noise image frequency rejection and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple frequency multiplication method is used to generate local oscillator signal, then terahertz frequency can be achieved, but noise performance deteriorates significantly
Solution Approach 1:
The frequency multiplication process is segmented into multiple stages with intermediate filtering. The system uses a series of frequency multipliers (e.g., x2, x3, x4) with band-pass filters between stages to selectively pass the desired frequency while blocking harmonics and noise, thereby achieving high frequency multiplication while controlling noise accumulation
Solution Approach 2:
Band-pass filters are introduced as intermediary components between frequency multiplication stages. These filters act as mediators that selectively transmit the desired frequency component while attenuating unwanted harmonics and noise, preventing noise degradation from propagating through subsequent multiplication stages
2Volume of stationary object
If circuits are simply integrated to reduce system volume, then portability is achieved, but processing difficulty and mutual interference increase
Solution Approach 1:
The integrated circuit is segmented into distinct functional modules (frequency multiplier modules, mixing modules, filtering modules) with clear spatial separation. Each module is designed and processed independently using standardized fabrication processes, reducing overall processing difficulty while maintaining compact integration
Solution Approach 2:
The circuit architecture transitions from planar two-dimensional layout to three-dimensional vertical integration. Different functional layers are stacked vertically with controlled inter-layer coupling, achieving high integration density while maintaining processing simplicity through standardized layer fabrication
3Manufacturing precision
If manual assembly is used for precise terahertz circuit assembly, then circuit precision can be achieved, but assembly errors and performance inconsistency increase
Solution Approach 1:
The invention replaces manual mechanical assembly with automated fabrication processes. Circuit components are fabricated using photolithography and other semiconductor manufacturing techniques, eliminating manual positioning errors and ensuring consistent performance across multiple circuits through precise, repeatable manufacturing
4Device complexity
If conventional mixer architecture is used, then circuit simplicity is maintained, but image frequency rejection capability is weak
Solution Approach 1:
The mixer architecture is segmented into multiple mixing paths with independent local oscillator phases. By using multiple mixers with phase-shifted local oscillator signals (e.g., 0° and 90° phases), the system can selectively cancel image frequency components through coherent addition, achieving high image rejection while maintaining reasonable circuit complexity
Solution Approach 2:
The mixer design employs asymmetric signal routing and phase shifting to create deliberate phase differences between signal paths. This asymmetry enables the system to distinguish between desired signal and image frequency components, achieving high image frequency rejection capability
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 effectively reduces circuit size while enhancing noise performance and image frequency rejection, ensuring consistent performance across multiple circuits and achieving integration and miniaturization of the entire terahertz image frequency rejection transceiver front-end.
Implementation Method 1
The 135° 3 dB filter coupler includes an input unit, a first output unit, a second output unit, and an isolation unit each of which is composed of a resonant cavity and a waveguide, and the resonant cavities of the input unit, the first output unit, the isolation unit, and the second output unit are sequentially coupled through resonant grooves to form a ring structure
Data Source
AI summary
The present disclosure provides a hetero-integrated terahertz low-noise miniaturized image frequency rejection transceiver front-end, including an intermediate frequency circuit and a terahertz circuit arranged up and down, where the terahertz circuit includes a local oscillator frequency tripler, a 135° 3 dB filter coupler, a radio frequency waveguide power divider, and two quartz hetero-integrated subharmonic mixers; resonant cavities of an input unit, a first output unit, an isolation unit, and a second output unit of the 135° 3 dB filter coupler are sequentially coupled through resonant grooves to form a ring structure, a cavity length of the resonant cavity of the input unit is twice that of the resonant cavities of the other three units, and an electrical length of a waveguide of the first output unit is 45° different from that of a waveguide of the second output unit.