TCXOs employing NS-GT cut quartz crystal resonators for cellular telephones

This paper describes temperature compensated crystal oscillators (TCXOs) employing new shape GT cut quartz crystal resonators (NS-GT cut resonators) to be used in cellular telephones. The NS-GT-TCXO has an oscillation frequency of 2.4 MHz and a frequency stability of ±1.5 ppm within a temperature range of -20°C to +70°C using a simplified temperature compensation method. These superior characteristics can be achieved with low current consumption (approximately 0.8 mA) and compactness (11.5 mm×8 mm×4 mm). Additionally, the phase-noise characteristics of the NS-GT-TCXO have been evaluated. The phase-noise value of the phase-locked loop circuit using the NS-GT-TCXO as a reference oscillator is approximately -70 dBc/Hz at 50 Hz offset from the 614.4 MHz carrier. This meets the requirements for use in cellular telephones. These results indicate that the miniaturization and low power consumption of the NS-GT-TCXO could have an important impact on the development of future cellular telephone systems