Temperature compensated crystal oscillator based on current conveyor and thermistor network

This paper presents the design of a TCXO(Temperature Compensated Crystal Oscillator) using a translinear second generation current conveyor(CCII) and a thermistor network. The CCII circuit, having a significantly wider bandwidth than voltage mode circuits, is implemented by the modified Fabre-Normand circuit. The frequency deviation of an AT-cut crystal is compensated using thermistors with temperature coefficients of opposite polarities. The designed CCII circuit was fabricated using 0.25μm standard CMOS process and the thermistor network was realized by off-chip circuits. The measured frequency deviation was ±4ppm for the temperature range from -20 °C to 70 °C.