Terahertz Oscillator Parasitic Suppression via Phase-Shifted Injection Locking
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Solution Overview
Problem
Existing terahertz wave oscillators experience parasitic oscillations in high frequency bands due to wiring structures, which reduce oscillation output and stability, and existing configurations do not effectively suppress these parasitic oscillations.
Innovation Solution
The oscillator configuration includes a resonance unit with two negative resistance elements connected in parallel, a bias circuit, and a line connecting the bias circuit to the resonance unit, where mutual injection locking in a reversed phase is stabilized, and the positive phase is destabilized, reducing parasitic oscillations by optimizing the coupling coefficient and antenna structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bias circuit with power source and wiring is used to adjust bias voltage of the negative resistance element, then the terahertz wave oscillation can be controlled, but parasitic oscillation occurs in low frequency band which decreases oscillation output at desired frequency
Solution Approach 1:
The patent extracts and separates the bias circuit from the resonance unit by placing them on different substrates. The bias circuit is mounted on a first substrate while the resonance unit with negative resistance element is on a second substrate, connected through a connection portion. This physical separation removes the bias circuit wiring from the high-frequency oscillation path, eliminating the parasitic oscillation source while preserving bias control functionality.
Solution Approach 2:
The patent introduces a connection portion as an intermediary element between the bias circuit and resonance unit. This connection portion acts as a mediator that provides electrical connection for bias voltage while being designed to minimize its impact on high-frequency oscillation characteristics, thus allowing bias control without introducing parasitic oscillation.
2Object-generated harmful factors
If inductance L is increased to decrease resonance frequency fLC, then parasitic oscillation at low frequency is reduced, but resistive loss at frequency fLC is increased which decreases oscillation output
Solution Approach 1:
The patent removes the source of parasitic oscillation by extracting the bias circuit wiring from the resonance structure. Instead of modifying L and C to suppress parasitic oscillation, the design separates the bias circuit from the resonance unit, eliminating the need to trade off inductance values and avoiding the associated resistive loss penalty.
3Object-generated harmful factors
If low impedance circuit is arranged on outer side of strip line, then parasitic oscillation at low frequency is suppressed, but parasitic oscillation in high frequency band (higher than 3 GHz) caused by wiring structure may occur
Solution Approach 1:
The patent extracts the bias circuit from the high-frequency signal path by placing it on a separate substrate. This eliminates the wiring structure that causes parasitic oscillation in high frequency bands while maintaining the ability to supply bias voltage, thus achieving both parasitic suppression and broad frequency adaptability.
Solution Approach 2:
The patent transitions from a planar arrangement where bias circuit and resonance unit share the same substrate to a three-dimensional configuration where they are mounted on different substrates. This dimensional change allows the bias circuit to be physically separated from the high-frequency oscillation path, suppressing parasitic oscillation across all frequency bands while maintaining electrical connection functionality.
4Productivity
If multiple negative resistance elements are used to improve oscillation output through injection locking, then terahertz wave generation is enhanced, but parasitic oscillation from bias circuit wiring increases
Solution Approach 1:
The patent extracts the bias circuit from the resonance unit and places it on a separate substrate. This allows multiple negative resistance elements to be used in the resonance unit for enhanced oscillation output through injection locking, while the separated bias circuit eliminates the parasitic oscillation that would otherwise be introduced by wiring to multiple elements.
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 configuration effectively suppresses parasitic oscillations in high frequency bands, stabilizing terahertz wave oscillation at the desired frequency, leading to increased output and reduced multi-oscillation, thereby enhancing the oscillation output by an order of magnitude.
Implementation Method 1
an element that can oscillate the terahertz wave in which a double barrier type resonant tunneling diode (RTD: Resonant Tunneling Diode) corresponding to a negative resistance element and a micro strip antenna are integrated on the same substrate exists
Implementation Method 2
a plurality of negative resistance elements are locked in a positive phase or a negative phase with each other to improve an oscillation output of the terahertz wave
Implementation Method 3
a resonance unit including a first conductor, a second conductor, a dielectric arranged between the first conductor and the second conductor
Implementation Method 4
PTL 1 describes that, in an oscillator in which an antenna is integrated in a plurality of negative resistance elements, the plurality of negative resistance elements are locked in a positive phase or a negative phase with each other to improve an oscillation output of the terahertz wave
Data Source
AI summary
Provided is an element that can reduce a parasitic oscillation. An element used for an oscillation or a detection of a terahertz wave includes a resonance unit 108 including a first conductor 102, a second conductor 105, a dielectric 104 arranged between the first conductor and the second conductor, a first negative resistance element 101a and a second negative resistance element 101b mutually connected in parallel between the first conductor and the second conductor, a bias circuit 120 that supplies a bias voltage to each of the first negative resistance element and the second negative resistance element, and a line 103 that connects the bias circuit to the resonance unit, and the element is configured in a manner that a mutual injection locking in a positive phase between the first negative resistance element and the second negative resistance element is unstable, and a mutual injection locking in a reversed phase between the first negative resistance element and the second negative resistance element becomes stable.