Realization of Voltage Controlled Temperature Compensated Crystal Oscillator with Single Varactor

The implementation of a voltage controlled temperature compensated crystal oscillator (VCTCXO) with a single varactor is presented. The proposed technique can overcome deficiencies of complicated nonlinear frequency calculation formula and temperature-frequency curve rotation caused by the oscillating circuit composed of multi capacitance diodes. With this technique, the VCTCXO has achieved the frequency stability up to ±1ppm with nearly ±100ppm output frequency variation range when the ambient temperature ranges from -30 °C to +70 °C by using 12.8 MHz fundamental AT-cut crystal resonator.