Dual-Sensor OCXO Temperature Control for Frequency Stability
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Solution Overview
Problem
Existing oven controlled crystal oscillators (OCXO) face challenges in achieving highly sensitive and accurate temperature control of resonators due to reliance on thermistor detection signals, leading to reduced frequency accuracy.
Innovation Solution
The oscillator incorporates a dual temperature sensing system with a first temperature sensing element near the resonator and a second element farther away, along with an analog/digital conversion circuit and digital signal processing circuit to generate a temperature control code, which corrects for temperature fluctuations using a combination of temperature codes and power supply voltage codes, enabling precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature control is performed based only on the detection signal of the thermistor, then the structure remains simple, but the accuracy of temperature control is reduced
Solution Approach 1:
The temperature sensing function is divided into two separate sensing elements: a first temperature sensing element positioned near the resonator to detect resonator temperature, and a second temperature sensing element positioned farther away to detect outside air temperature. This segmentation allows each sensor to perform its specific function optimally, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
A digital signal processing circuit acts as an intermediary that receives temperature detection signals from both sensing elements, converts them to digital values, and generates a temperature control code by combining both inputs. This intermediary processing enables accurate temperature control by synthesizing information from both local and environmental temperature sources.
2Adaptability or versatility
If a single temperature sensing element is used, then the device complexity is low, but the ability to detect both resonator temperature and outside air temperature fluctuations is insufficient
Solution Approach 1:
The temperature sensing function is divided into two separate sensing elements: a first temperature sensing element positioned near the resonator to detect resonator temperature, and a second temperature sensing element positioned farther away to detect outside air temperature. This segmentation allows each sensor to perform its specific function optimally, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The dual temperature sensing system provides multi-functionality by simultaneously detecting both resonator temperature and outside air temperature, enabling the oscillator to adapt to various thermal conditions and maintain frequency accuracy regardless of environmental changes.
3Reliability
If temperature control is based only on thermistor detection, then the system remains simple, but frequency accuracy is reduced due to inability to correct for outside air temperature fluctuations
Solution Approach 1:
The digital signal processing circuit implements feedback by continuously monitoring temperatures from both sensing elements and dynamically adjusting the temperature control code based on the combined information, ensuring frequency accuracy is maintained despite environmental temperature fluctuations.
Solution Approach 2:
A digital signal processing circuit acts as an intermediary that receives temperature detection signals from both sensing elements, converts them to digital values, and generates a temperature control code by combining both inputs. This intermediary processing enables accurate temperature control by synthesizing information from both local and environmental temperature sources.
4Measurement precision
If only one temperature sensing element is used, then the device complexity is low, but the temperature control accuracy under varying power supply conditions is reduced
Solution Approach 1:
The temperature sensing function is divided into two separate sensing elements: a first temperature sensing element positioned near the resonator to detect resonator temperature, and a second temperature sensing element positioned farther away to detect outside air temperature. This segmentation allows each sensor to perform its specific function optimally, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
A digital signal processing circuit acts as an intermediary that receives temperature detection signals from both sensing elements, converts them to digital values, and generates a temperature control code by combining both inputs. This intermediary processing enables accurate temperature control by synthesizing information from both local and environmental temperature sources.
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 enhances the accuracy of temperature control, reducing the likelihood of frequency deviations caused by outside air temperature fluctuations and power supply variations, thereby improving the stability of the oscillation signal.
Implementation Method 1
a first temperature sensing element that outputs a first temperature detection signal
Implementation Method 2
a second temperature sensing element that is provided at a position farther from the resonator than the first temperature sensing element and outputs a second temperature detection signal
Implementation Method 3
a heating element that heats a resonator
Implementation Method 4
an analog/digital conversion circuit that converts the first temperature detection signal into a first temperature code which is a digital signal, and converts the second temperature detection signal into a second temperature code which is a digital signal
Data Source
AI summary
An oscillator includes a resonator, a temperature control element that controls a temperature of the resonator, a first temperature sensing element that outputs a first temperature detection signal, a second temperature sensing element that is provided at a position farther from the resonator than the first temperature sensing element and outputs a second temperature detection signal, an analog/digital conversion circuit that converts the first temperature detection signal into a first temperature code which is a digital signal, and converts the second temperature detection signal into a second temperature code which is a digital signal, and a digital signal processing circuit that generates a temperature control code for controlling the temperature control element based on the first temperature code and the second temperature code.