Oven Oscillator Temperature Compensation Using External Sensor Input
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Solution Overview
Problem
Existing oscillators, such as OCXO and TCXO, face challenges in achieving high accuracy of oscillation frequency due to temperature variations, as the internal temperature sensors within the circuit devices have limited resolution and are prone to noise, leading to inaccuracies in temperature compensation.
Innovation Solution
A circuit device with an external temperature sensor input terminal allows for the use of external temperature sensors, which provide higher resolution temperature detection data, and a programmable gain amplifier adjusts the gain according to the sensor characteristics, while a digital filter reduces noise in the temperature detection voltage, enabling precise temperature compensation and aging correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an internal temperature sensor is used within the circuit device, then the temperature can be measured, but the resolution of temperature detection becomes low due to small variation range
Solution Approach 1:
An external temperature sensor is introduced as an intermediary component to measure the ambient temperature of the thermostatic oven. This external sensor provides a broader temperature variation range for detection, improving the resolution of temperature measurement. The sensor output is then fed into the circuit device through a dedicated input terminal, separating the measurement function from the control circuitry.
Solution Approach 2:
The temperature measurement is shifted from an internal dimension (inside the thermostatic oven where temperature variation is small) to an external dimension (ambient temperature where variation range is larger). This dimensional change allows the A/D conversion circuit to operate with sufficient resolution by capturing temperature variations over a broader range.
2Measurement precision
If the temperature sensor is disposed inside the thermostatic oven, then the temperature of the resonator can be measured, but the sensing voltage variation range becomes extremely small
Solution Approach 1:
The external temperature sensor acts as a mediator that indirectly measures the thermal conditions affecting the resonator without being subjected to the limited temperature variation inside the thermostatic oven. By measuring ambient temperature, the sensor provides sufficient voltage variation for accurate A/D conversion and subsequent temperature compensation.
3Productivity
If the A/D conversion circuit uses the internal temperature sensor output, then the temperature detection can be performed, but the code variation range becomes small leading to low resolution
Solution Approach 1:
The external temperature sensor serves as an intermediary that provides a temperature signal with sufficient variation range. This signal, when input to the A/D conversion circuit, ensures adequate code variation across the converter's full scale, thereby maintaining high resolution in temperature detection and compensation.
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 configuration enhances the stability of oscillation frequency by improving temperature resolution and reducing frequency correction errors, achieving low temperature dependency and accurate aging correction, thus ensuring high-frequency accuracy and stability.
Implementation Method 1
the temperature of the resonator is measured by a temperature sensor
Implementation Method 2
the sensing voltage of the temperature sensor is A/D converted by an A/D conversion circuit
Implementation Method 3
the control is performed so that the oscillation frequency becomes constant based on the temperature thus measured
Implementation Method 4
an oscillation signal with the oscillation frequency corresponding to the frequency control data using the frequency control data and an oven-type resonator
Data Source
AI summary
A circuit device includes a processor adapted to perform a signal processing of temperature compensation of an oscillation frequency based on temperature detection data from an external temperature sensor disposed outside the circuit device to output frequency control data, and an oscillation signal generation circuit adapted to generate an oscillation signal with the oscillation frequency corresponding to the frequency control data using the frequency control data and a resonator disposed in a thermostatic oven.