TCXO oscillators are Temperature Compensated Crystal Oscillators, a type of crystal oscillator. These oscillators are used when a precision frequency source is needed within a narrow space and at a reasonable cost. You can improve the basic performance of the crystal by applying temperature compensation that falls within the quartz crystal oscillator module. Because of their properties, they are widely available in the market in various packaging and mounting options. Some TCXOs are even compatible with the dual in-line format utilized for many through-hole mounted integrated circuits.
These oscillators usually have a temperature-sensitive reactance circuit in their oscillation loop to compensate for the frequency-temperature properties of inheriting the crystal unit.
Elements of Temperature Controlled Oscillator
5 elements make the entire temperature-controlled oscillator.
The Compensation Network
The compensation network is the way into the activity of the entire framework. A rough curve for the temperature frequency reaction of the oscillator has been seen previously. The natural curve can be communicated roughly as a third-order polynomial articulation. However, a more exact portrayal considers some non-linearities and works out to be near a fifth-order polynomial. The compensation network requires detecting the temperature and producing a voltage that is the inverse of this.
Early designs would have utilized simple hardware and straightforwardly utilized an organization of capacitors, resistors, and thermistors to control oscillation frequency. This kind of circuit features the two blocks for the graph of the compensation organization and the crystal frequency pulling block.
The Oscillator Pulling Circuit
After the generation of voltage, it is applied to a circuit that can effectively pull the frequency of the crystal oscillator. Commonly, this consist of a varactor diode and a low pass filtering.
The Crystal Oscillator Circuit
Crystal oscillator circuits are usually standard circuits. However, these are designed for the operating condition of the crystal with suitable drive levels.
The Voltage Regulator
TCXO oscillators need to have a voltage regulator to prevent any external voltage changes from creating any unwanted frequency shifts. It is crucial to use voltage regulators that do not create unwanted temperature effects.
The Buffer Amplifier
The buffer amplifier is an important element as it gives an increased drive to the output. It isolates the crystal oscillator from any visible external load changes. TCXOs usually have an external adjustment that can reset the frequency at regular intervals. This helps in avoiding the ageing of the crystals. The time between the calibration adjustments heavily depends upon the accuracy required but is usually for six months or even a year. If high levels of accuracy are required, may use the shorter periods.
Minimizing the Effects of Temperature
Even though crystal oscillators are the most stable form of oscillators, they can still be effected by temperature. The type of crystal cut within the oscillator is used to minimize the effects of temperature, but they are still not completely safe and can be effected to a certain extent.
With a crystal cut called AT-cut, the drift with temperature can be decreased to normal ambient temperature, but there is potential for the rate of drift to fluctuate above and below this.
Conclusion
With such complicated composition and a wide range of properties, it can be a little difficult to understand the TCXO oscillator. However, with the specifications provided on our website, you can choose the product suited just for your application.
