Analog TCXO using cubic functional voltage generator

This paper describes an indirect analog TCXO (Temperature-Compensated Crystal Oscillator) which has achieved a temperature compensation functioning much more accurately in view of the theoretical f-T behavior of crystal unit than those expected at present. This TCXO consists of two blocks. One is a temperature compensation circuit which fits in well with IC process, which outputs cubic functional variation of voltage with temperature (it consists of cubic and linear terms), while the other is VCXO (Voltage Controlled Crystal Oscillator), which has good linearity of frequency-control voltage characteristics (f-Vc characteristics). The TCXO achieved ±1[ppm]/-30~85[°C] (crystal resonator: ±25[ppm]/-30~85[°C]) in laboratory measurements. This paper discusses the device with an emphasis on its temperature compensation circuit