Wireless Chipset Clock Compensation Using Crystal Temperature Sensing
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Solution Overview
Problem
Existing wireless communication devices face challenges in achieving precise frequency accuracy over a wide range of temperatures due to the limitations of temperature-compensated crystal oscillators, which increase design complexity and cost without providing frequency error feedback to the system.
Innovation Solution
A wireless device utilizing a non-compensated crystal oscillator with a temperature measuring device and a controller to estimate frequency errors, allowing for digital clock and rotator adjustments to compensate for temperature-dependent frequency drift, thereby maintaining accurate frequency translation in both receive and transmit paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature compensated crystal oscillator (TCXO) or voltage controlled TCXO (VCTCXO) is used to generate a reference signal with frequency compensation, then frequency precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the temperature compensation function from the crystal oscillator hardware and relocates it to the digital signal processor. Instead of using a complex TCXO circuit, the system measures temperature with a sensor and computationally compensates for frequency drift in the digital domain, thereby reducing hardware complexity while maintaining frequency precision.
Solution Approach 2:
The patent replaces the mechanical/physical temperature compensation mechanism (TCXO circuitry) with a digital computational approach. The frequency compensation is achieved through software algorithms that calculate and apply corrections based on temperature measurements, substituting electronic hardware with digital processing.
2Measurement precision
If a temperature compensated crystal oscillator is used, then frequency accuracy over temperature range is improved, but cost increases
Solution Approach 1:
The patent uses inexpensive components (standard crystal oscillator and temperature sensor) that can be easily manufactured and replaced, rather than expensive TCXO modules. The cost-effective approach relies on digital processing power to achieve the same performance as costly hardware compensation circuits.
3Measurement precision
If a temperature compensated crystal oscillator is used, then frequency precision is improved, but the system cannot act on frequency error information
Solution Approach 1:
The patent implements a feedback mechanism where the digital signal processor continuously monitors temperature, calculates frequency errors based on calibrated models, and applies real-time corrections. The system also provides frequency error information to the overall system, enabling adaptive adjustments and closed-loop control for optimal 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 enables good performance with a 'clean' sampling clock, accurate digital processing, and effective frequency error correction, avoiding degradation from spectral components and ensuring reliable communication across temperature variations.
Implementation Method 1
a temperature measuring device within the package
Data Source
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AI summary
An apparatus includes a temperature measuring device within a thermally conductive package. A crystal within the package is thermally coupled to the temperature measuring device and subjected to a same temperature as the temperature measuring device. A controller external to the package is configured to receive a signal from the crystal and a temperature measurement from the temperature measuring device. The controller is configured to estimate a frequency error of the crystal based on the temperature measurement and to provide a frequency error estimate to an external system.