Temperature-Compensated Timing Generator With Fractional Pulse Correction
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Solution Overview
Problem
Existing timing signal generators with quartz crystal oscillators face accuracy issues due to temperature variations, as current compensation methods like pulse inhibition and injection have limited resolution, leading to quantification errors and frequency deviations.
Innovation Solution
A temperature compensated timing signal generator that employs inhibition and/or injection compensation for coarse thermal correction, along with fractional inhibition for finer interpolation, using a high frequency oscillator and temperature sensors to provide precise timing signals by adjusting the onset of edges and incorporating fractional deviation compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If pulse inhibition or injection compensation is used for temperature compensation, then temperature stability is improved, but measurement precision deteriorates due to quantification error limiting resolution to 30.5 ppm
Solution Approach 1:
The invention segments the compensation process into two distinct stages: coarse compensation using traditional pulse inhibition/injection methods, and fine compensation using a digitally controlled delay element. This segmentation allows each stage to operate at its optimal resolution level, with the fine compensation stage providing the additional precision needed to overcome the quantification error limitation of the coarse stage.
Solution Approach 2:
The invention introduces a digitally controlled delay element as an intermediary component between the coarse compensation mechanism and the final timing signal output. This intermediary provides continuous adjustable delay that can fine-tune the timing signal with resolution much finer than the discrete pulse inhibition/injection method, effectively bridging the gap between coarse temperature compensation and high-precision timing requirements.
2Stability of the object's composition
If traditional pulse inhibition/injection compensation is used, then temperature compensation is achieved, but device complexity increases due to requirement of waiting at least 31 seconds for 1 ppm resolution
Solution Approach 1:
The invention performs preliminary coarse temperature compensation using pulse inhibition or injection methods to bring the timing signal close to the desired frequency. This preliminary action reduces the magnitude of subsequent fine adjustments needed, allowing the system to achieve high precision without requiring extremely long observation periods that would be necessary if relying solely on fine compensation mechanisms.
Solution Approach 2:
The invention dynamically switches between two compensation mechanisms: using the fast-acting but low-resolution pulse inhibition/injection method for coarse adjustments, and the slow-acting but high-resolution digitally controlled delay element for fine adjustments. This dynamic approach optimizes the overall response time and complexity by utilizing each mechanism in the regime where it is most effective.
3Measurement precision
If high frequency oscillator is introduced for fractional inhibition, then measurement precision is improved to 1 ppm resolution, but device complexity increases
Solution Approach 1:
The invention replaces the mechanical/quartz crystal-based frequency division approach with a digitally controlled delay element that uses electronic timing control. This substitution allows for continuous adjustment of the timing signal with high precision without requiring complex mechanical frequency division networks, thereby achieving 1 ppm resolution with relatively simple electronic circuitry.
Data Source
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AI summary
The temperature compensated timing signal generator comprises a crystal oscillator (12; 112) configured to generate a reference time signal, and a divider circuit (14, 114) arranged to receive the reference time signal as input and to output a coarse time unit signal, the coarse time unit signal having an actual frequency deviating from a desired frequency as a function of temperature of said crystal oscillator. The signal generator also includes a high frequency oscillator (16; 116) configured to generate an interpolation signal having a frequency (fRC) greater than the frequency (fXT) of the crystal oscillator. A finite state machine (24; 124) computes a deviation compensating signal as a function of temperature, the signal comprises an integer part representative of an integer number of pulses to be inhibited or injected in the divider circuit (14; 114) and a fractional part representative of how much the output of a new time unit signal pulse should further be delayed in order to compensate for any remaining deviation.