PURPOSE: To perform a compensation for frequency temperature of a quartz oscillator, by making use of the resistance temperature variation of a resistor having a positive and negative resistance temperature coefficient.

CONSTITUTION: The resistance values of resistors 12 and 13 are expressed by R2 and R3 respectively, and these values are set to be equal to each other at a level near the normal tempratures. Thus the parallel resistance value shows the highest level near the normal temperatures and are lowered at a level higher or lower than the normal temperatures. Making use of this resistance temperature characteristics, the parallel resistance values of resistors 12 and 13 become maximum near the normal temperatures for a quartz oscillator. At the same time, the time constant also becomes maximum to the output terminal capacity 10. Thereafter, the parallel resistance values of resistors 12 and 13 begin to lower by the temperature to lower the time constant to the capacity 10. As a result, for the extent of the frequency variation, the phase difference between the input and output is reduced for the oscillation inverter 7 as the time constant is reduced. This results in a gain. In other words, a compensation is given to the frequency temperature in the forward direction. The figure 8 shows a feedback resistor in the diagram.