High precision TCXO for rapid environmental temperature change

Abstract

Recently, the increased high speed of the transmission of mobile communication devices has necessitated higher stabilization of oscillators. Also, mobile communication devices are becoming more miniaturized. It is estimated the downsizing of a high precision frequency source will become necessary, too. Therefore, the method to get a precise frequency more easily is necessary. We study TCXOs to produce a small-sized high precision frequency source. When making small-sized TCXOs, TCXOs are strongly influenced by the environmental temperature. Currently, high stability must be kept in rapid environmental temperature change. But, because the temperature sensor and the crystal resonator have different thermal time constants, the frequency stability of TCXOs in rapid environmental temperature change is generally poor. In this paper, we propose that the temperature estimate method of the change in rapid and complicated environmental temperature can be used, as a way of compensating for the temperature characteristic of TCXOs. We focus on using the temperature change of a sensor and a crystal resonator as the lag function. This method is the way of compensating for the temperature characteristic using the temperature estimate function. The temperature estimate function can support nth derivative of temperature T with respect to time t. As a result, we have shown that it is possible to compensate frequency estimate with fewer errors in rapid environmental temperature change for which conventional TCXOs cannot compensate. Next, we confirm that our proposed TCXO is useful by using simulation with actual circuit parameters and experiments. As an example, we applied this method to conventional TCXOs that have the estimated error of more than /spl plusmn/10[ppm]. As a result, we have shown that it is possible to decrease errors to less than /spl plusmn/0.01[ppm].