Oscillator Calibration Using Phase Tracking and Divisor Adjustment
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Solution Overview
Problem
Conventional methods for calibrating the dynamic and static ranges of oscillators in wireless communication systems are time-consuming and costly, and fail to effectively account for temperature variations and crystal aging, due to non-linear relationships between AFC codes and oscillating frequencies.
Innovation Solution
A calibration device comprising a phase locking device, an adjusting circuit, and a calibrating circuit that tracks reference clocks and adjusts divisors to reduce static phase differences, allowing for the calibration of oscillating frequencies and linearization of characteristic curves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional off-chip instruments are used to test the static range and dynamic range of an oscillator, then measurement can be performed, but the testing process is time-consuming and involves extra costs
Solution Approach 1:
The patent introduces an on-chip calibration device as an intermediary component that bridges the oscillator and measurement functions. This calibration device includes a phase locking device, adjusting circuit, and calibrating circuit that work together to enable self-calibration and measurement without requiring external off-chip instruments, thereby reducing testing time and costs while maintaining measurement capability
Solution Approach 2:
The oscillator system is equipped with integrated calibration and measurement circuits that enable it to perform self-testing and self-calibration. The phase locking device tracks reference clocks, the adjusting circuit modifies divisor values, and the calibrating circuit determines characteristic curves, allowing the system to measure its own performance without external intervention, thus eliminating time-consuming external testing procedures
2Adaptability or versatility
If the relation between AFC code and oscillating frequency is non-linear in practice, then the oscillator can operate, but the system does not have enough margins to track temperature variation and crystal aging
Solution Approach 1:
The calibration device performs preliminary characterization of the oscillator's non-linear frequency response by measuring the actual relationship between AFC codes and oscillating frequencies under different conditions. This preliminary data is stored and used to pre-compensate for temperature variations and crystal aging effects, enabling the system to maintain frequency stability without requiring large margins during operation
Solution Approach 2:
The system dynamically adjusts the divisor parameter in the phase locking device based on measured characteristic curves. By changing the divisor value according to the calibrated non-linear relationship, the system compensates for frequency drift caused by temperature and aging, thereby maintaining reliable frequency stability while adapting to environmental changes
3Measurement precision
If the characteristic curve of the oscillator is non-linear, then the oscillator operates, but conventional calibration methods are insufficient to correct the frequency accuracy
Solution Approach 1:
The calibration process is segmented into distinct functional modules: a phase locking device for tracking reference clocks, an adjusting circuit for modifying divisor values, and a calibrating circuit for determining characteristic curves. This segmentation allows each module to perform its specific function efficiently, making the overall calibration system manageable and effective in correcting non-linear frequency responses
Solution Approach 2:
The calibration device implements a feedback mechanism where the phase locking device continuously compares the oscillator output with reference clocks, detects phase differences, and feeds this information back to the adjusting circuit. The adjusting circuit modifies the divisor based on this feedback, and the calibrating circuit uses the accumulated data to determine and correct the characteristic curve, thereby systematically improving frequency accuracy through iterative feedback control
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 provides an efficient and cost-effective method to calibrate oscillators, improving their frequency stability and accuracy by reducing static phase differences and making the characteristic curves linear, thus addressing the limitations of existing calibration techniques.
Implementation Method 1
the phase locking device is arranged to track a first reference clock generated by the oscillator until a feedback clock is phase-aligned with the first reference clock, and then arranged to track a second reference clock generated by the oscillator until a phase difference between the second reference clock and the feedback clock is a static phase difference
Data Source
AI summary
A calibration device arranged for calibrating an oscillating frequency of an oscillator includes: a phase locking device arranged to track a first reference clock generated by the oscillator until a feedback clock is phase-aligned with the first reference clock, and then arranged to track a second reference clock generated by the oscillator until a phase difference between the second reference clock and the feedback clock is a static phase difference, wherein the feedback clock is generated by dividing an output oscillating signal of the phase locking device by a divisor; an adjusting circuit arranged to adjust the divisor into an updated divisor to reduce the static phase difference between the second reference clock and the feedback clock; and a calibrating circuit arranged to calibrate the oscillating frequency of the oscillator according to the updated divisor, wherein the second reference clock is generated by varying a control signal of the oscillator.