Atomic Clock Bias Correction Circuit for Low Allan Deviation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Molecular clocks face frequency accuracy issues due to sensitivity to process, voltage, and temperature variations, which introduce bias and impact signal-to-noise ratio and Allan deviation, particularly when correlating with higher order harmonics to reduce bias sensitivity.
Innovation Solution
A bias correction circuit utilizing both frequency and amplitude modulation to generate tuning signals that compensate for PVT variations, incorporating a digital processing circuit, frequency modulator, amplitude modulator, and adder to adjust the frequency and amplitude modulation parameters, thereby maintaining alignment with the absorption frequency of the physics cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If molecular clocks correlate with higher order, odd harmonics to reduce bias sensitivity, then bias sensitivity is reduced, but signal-to-noise ratio decreases
Solution Approach 1:
The patent segments the frequency tuning control into multiple independent components: a bias correction signal path and a frequency tuning signal path. The bias correction circuit processes the output signal separately to generate correction parameters, which are then combined with the frequency tuning signal. This segmentation allows optimization of each path independently - the bias correction path can use higher order harmonics for reduced sensitivity while the frequency tuning path maintains signal-to-noise ratio
Solution Approach 2:
The patent introduces an intermediary bias correction circuit that acts as a mediator between the output signal and the frequency tuning control. This circuit generates bias correction parameters by correlating with higher order harmonics and combines them with the frequency tuning signal through addition. The intermediary structure allows the system to benefit from reduced bias sensitivity without directly degrading the main signal-to-noise ratio path
2Productivity
If molecular clocks use frequency modulation to amplitude modulation conversions, then clock signals can be generated, but frequency-dependent bias is introduced
Solution Approach 1:
The patent implements a feedback mechanism where the output signal from the physics cell is correlated with the frequency modulation signal to generate bias correction parameters. These parameters are fed back to adjust the frequency tuning control, creating a closed-loop system that continuously compensates for frequency-dependent bias while maintaining clock signal generation functionality
Solution Approach 2:
The patent converts the harmful frequency-dependent bias into a useful correction signal. By correlating the output signal with the frequency modulation signal and processing the correlation output, the system generates bias correction parameters that actively compensate for the bias. The harmful bias effect is transformed into informative data that drives the correction mechanism
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 bias sensitivity, improving frequency accuracy and signal-to-noise ratio by continuously tracking the absorption frequency across PVT variations, maintaining alignment and reducing noise-induced deviations.
Implementation Method 1
The frequency modulator generates a frequency modulation signal
Implementation Method 2
The amplitude modulator receives the amplitude modulation parameter and generates an amplitude modulation signal
Implementation Method 3
The physics cell receives the amplitude-modulated and frequency-modulated transmit frequency signal and generates an absorption signal
Data Source
AI summary
A system comprises a digital processing circuit, a frequency modulator, an amplitude modulator, and an adder. The digital processing circuit receives an input signal and a correlation signal and generates a frequency tuning parameter and an amplitude modulation parameter. The frequency modulator generates a frequency modulation signal and the correlation signal. The amplitude modulator receives the amplitude modulation parameter and generates an amplitude modulation signal. The adder receives the frequency tuning parameter and the frequency modulation signal and generates a control signal. In some implementations, the system further comprises a DC feedback circuit that receives the input signal and generates a DC compensation signal. In some implementations, the system further comprises a temperature sensor, a temperature compensation circuit, and a second adder.