Realization of Voltage Controlled Temperature Compensated Crystal Oscillator with Single Varactor

Abstract

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 $\pm 1\mathbf{ppm}$ with nearly $\pm 100\mathbf{ppm}$ 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.