The Working Principles of TCXO

tcxo quartz is a kind of crystal oscillators who reducing its frequency deviation caused by surrounding temperature fluctuations via adding temperature compensated circuit.

For tcxo quartz, there are two types of compensation methods for quartz crystal frequency temperature drift. 

Direct compensation type of tcxo quartz

Direct compensation tcxo quartz is a temperature compensation circuit composed of thermistor and resistance components, which is connected with quartz chips in the oscillator. When temperature changes, the resistance value of the thermistor and the crystal equivalent of the heating resistance changes accordingly, thereby canceling or cutting the temperature drift of the oscillation frequency. The compensation method circuit is simple and low in cost, saving the size and space of printing circuit board (PCB), suitable for small and low -voltage small current occasions. However, when the accuracy of the crystal oscillator is less than ± 1pmm, the direct compensation method is not suitable. 

Indirect compensation type of tcxo quartz

Indirect compensation types are divided into two types: simulation and digital. The indirect temperature compensation of the simulation is to form a temperature-voltage transformation circuit using temperature sensing elements such as thermistor, and apply the voltage to a transformer diode connected to the quartz chip. Compensation for the non -linear frequency drift of the chip. This compensation method can achieve high accuracy of ± 0.5ppm, but it is limited in low voltage below 3V. Digital indirect temperature compensation is the temperature -the voltage transformation circuit in the analog compensation circuit adds a first -class mold/number (A/D) converter after the voltage transformation circuit to convert the simulation quantity into a digital amount. This method can achieve automatic temperature compensation, so that the frequency stability of the transistor oscillator is very high, but the specific compensation circuit is more complicated and the cost is high. It is only suitable for high -precision conditions such as base stations and radio stations.

The Advantages Of Differential Oscillators