Phononic Comb Oscillator With AM-to-PM Noise Cancellation
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Solution Overview
Problem
Current reference oscillators, such as TCXOs and OCXOs, face challenges in achieving low phase noise and timing jitter, especially at higher offset frequencies, while also requiring reduced size and power consumption, and higher stability than TCXOs with low g-sensitivity.
Innovation Solution
The implementation of a phononic comb enhanced oscillator with an AM-to-PM noise cancellation technique, where a phase correction is applied to the output of a nonlinear resonator to reduce noise, utilizing a voltage-controlled phase shifter and a filter to correlate and cancel the amplitude modulation noise with phase modulation noise, thereby improving phase noise performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reference oscillators (TCXO/OCXO) are used to achieve low phase noise and timing jitter, then phase noise performance is improved, but device size and power consumption increase
Solution Approach 1:
The patent changes the operating parameters of the resonator by driving it at multiple harmonics (fundamental frequency and overtone modes) to generate a frequency comb. This allows the system to achieve OCXO-level phase noise performance at TCXO size by utilizing harmonic relationships and frequency multiplication rather than physically enlarging the oscillator components.
Solution Approach 2:
The patent segments the frequency spectrum by generating a comb of equally spaced frequency components from a single resonator. By selecting specific comb teeth (harmonics) for output, the system achieves multiple frequency outputs with low phase noise without requiring multiple separate oscillators, thereby reducing overall device size while maintaining performance.
2Measurement precision
If conventional reference oscillators are used to achieve low phase noise and timing jitter, then phase noise performance is improved, but power consumption increases
Solution Approach 1:
The resonator performs multiple functions simultaneously: it generates the fundamental frequency, produces harmonic overtones, creates the frequency comb structure, and provides phase noise suppression. This multi-functionality eliminates the need for separate components that would increase power consumption, achieving OCXO performance at TCXO power levels.
Solution Approach 2:
The system changes the drive level and operating point of the resonator to optimize the generation of harmonic content while maintaining low phase noise. By carefully controlling the excitation parameters and selecting appropriate comb teeth, the system achieves high performance with minimal power consumption.
3Volume of moving object
If phononic comb enhanced oscillator is used to reduce device size and power consumption, then device size and power consumption are reduced, but phase noise and timing jitter performance deteriorates
Solution Approach 1:
The patent introduces an intermediary processing stage that analyzes the frequency comb spectrum and selectively enhances specific comb teeth while suppressing others. This intermediary processing allows the compact resonator to achieve low phase noise performance by filtering and selecting the cleanest frequency components, effectively mediating between the compact structure and high performance requirements.
Solution Approach 2:
The system employs feedback mechanisms to monitor and correct phase noise in the output signal. By detecting phase deviations and applying corrective feedback, the compact oscillator maintains timing jitter performance comparable to much larger conventional oscillators, closing the performance gap despite the reduced size.
4Measurement precision
If amplitude modulation noise is present in the drive signal, then phase modulation noise is generated in the phononic comb teeth, but this noise is correlated and can be cancelled
Solution Approach 1:
The patent converts the harmful AM-to-PM noise conversion effect into a beneficial cancellation mechanism. By detecting the correlated AM noise in the drive signal and using it to generate an opposing phase correction signal, the system transforms the noise generation mechanism into a noise cancellation tool, effectively reducing phase noise in the output.
Solution Approach 2:
The system applies preliminary anti-action by pre-correcting the phase noise before it propagates through the system. By detecting AM noise components in the drive signal and generating compensating phase adjustments in advance, the system prevents the harmful PM noise from fully developing, thereby improving overall phase noise performance.
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 phase noise and timing jitter, maintaining low electronic noise at far-from-carrier frequencies, and achieves higher stability with reduced size and power consumption, addressing the limitations of existing technologies.
Implementation Method 1
a phase correction is applied to the output of a nonlinear resonator to reduce noise, utilizing a voltage-controlled phase shifter
Implementation Method 2
Nonlinear effects such as Duffing in MEMS resonators have been explored in the past to improve phase noise
Implementation Method 3
an AM-to-PM noise cancellation technique, where a phase correction is applied to the output of a nonlinear resonator to reduce noise, utilizing a voltage-controlled phase shifter and a filter to correlate and cancel the amplitude modulation noise with phase modulation noise
Data Source
AI summary
A comb enhanced oscillator in which a drive signal from a first oscillator is split into two signals. The first signal is applied to a nonlinear resonator producing a phononic frequency comb of equally spaced resonances. The second signal is passed through an amplitude detector and a phase shifter. In one embodiment, the comb is applied to the phase shifter to correct for AM-PM cross-correlation noise and then applied to a phase lock loop (PLL) for locking to a second oscillator. The output of the second oscillator is used as the output of the comb enhanced oscillator.