Study and design of integrated crystal oscillator

A novel structure of the integrated cascode crystal oscillator is presented by analyzing the discrete oscillator circuits in this paper. A temperature-independent voltage source, which is suitable for integrated circuits, was used for biasing of the buffer amplifier, while eliminating the bypass capacitor. Both the oscillator circuits and the buffer amplifier use the common divider resistance. The improvements reduce the start-up time of the oscillator and the area of the layout. With the library of chrt.35dg_ SiGe, we simulate the oscillator circuits by the spectre simulation tools of the Cadence. The simulations show that: when the supply voltage is 2.7 V, the frequency, the start-up time and the peak-to-peak value of the output of the oscillator are 12.8 MHz, 1.3 mS and 0.8 V respectively. And the SSB (Single Side Band) phase noise is -142 dBc/Hz at 1 kHz, -150 dBc/Hz at 10 kHz. The power consumption of the circuits is less than 2.7 mW.