Microwave Oscillator Amplitude Noise Reduction via Baseband Feedback
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Solution Overview
Problem
Microwave oscillators face challenges in reducing amplitude noise, which can be significant even after phase noise reduction techniques are applied, limiting the overall noise level and affecting the quality of output signals used in various applications.
Innovation Solution
An amplitude noise reduction loop is implemented in the microwave oscillator, utilizing a baseband control signal generated by a Carrier Suppression Interferometer (CSI) to perform amplitude modulation of the oscillator feedback signal, which includes a high-pass filter and a Monolithic Microwave Integrated Circuit (MMIC) for effective noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase noise reduction techniques are applied to microwave oscillators, then phase noise is reduced, but amplitude noise becomes significant and limits the overall noise performance
Solution Approach 1:
The patent separates phase noise and amplitude noise into different signal paths using a 90-degree hybrid coupler. Phase noise is processed through one path while amplitude noise is processed through another path, allowing independent reduction techniques to be applied to each type of noise without interference.
Solution Approach 2:
The patent introduces an amplitude noise reduction loop as an intermediary system that takes the oscillator output, detects amplitude fluctuations, and generates a correction signal. This intermediary loop processes amplitude noise separately and feeds back to cancel amplitude variations while preserving phase noise reduction achievements.
2Object-generated harmful factors
If amplitude noise reduction is implemented in microwave oscillators, then amplitude noise is reduced, but device complexity increases
Solution Approach 1:
The 90-degree hybrid coupler serves multiple functions simultaneously: it separates phase and amplitude components, provides signal splitting for the feedback loops, and enables both phase noise and amplitude noise reduction paths. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The patent implements an amplitude noise reduction feedback loop that continuously monitors the oscillator output, detects amplitude fluctuations, and applies corrective feedback. The loop uses the oscillator output itself as the feedback signal, eliminating the need for separate sensing components and reducing overall system complexity.
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 effectively reduces amplitude noise in the oscillator output signal, improving the overall noise performance and ensuring high-quality sinusoidal or clock signals across various frequency bands, including microwave frequencies.
Implementation Method 1
combining a portion of the RF signal incident on the resonator with a reflection of the RF signal incident on the resonator
Implementation Method 2
mixing a first local oscillator (LO) reference signal with a mixer input signal to produce a first baseband control signal
Implementation Method 3
perform amplitude modulation (AM) of an oscillator feedback signal to produce an updated RF signal
Data Source
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AI summary
Embodiments of a microwave oscillator and method for amplitude noise reduction are generally described herein. The oscillator may include a resonator and an RF bridge to combine an incident and a reflected RF signal. The oscillator may further comprise an amplitude noise reduction loop, which may be configured to use a first baseband control signal to perform amplitude modulation (AM) of an oscillator feedback signal for reduction of amplitude noise on the oscillator output signal.