Integrated Circuits Laboratory, Electrical Engineering department, University of Zanjan, Zanjan, Iran
This paper presents a temperature compensation voltage controlled oscillator (VCO) based on Cross-Coupled pair and Colpitts structures which is suitable for military fields. Also, two inductors have been used for increasing the negative conductance. By using this method, start-up condition has been improved. Two varactors and a simple capacitor bank are applied for covering a wide tunning range. The VCO has been designed and simulated in TSMC 0.18 µm CMOS technology.To compensate the frequency drift over a temperature range, MOS varactors are used and biased with a complementary to absolute temperature (CTAT) voltage reference. This CTAT voltage reference has been applied to two varactors and decreased the frequncy drift over temperature range. By using this technique, the proposed VCO can achieve a very stable frequency of 11.5 PPM/°C at 24.35 GHz over a temperature range of -40~120 °C. Simulation results also show the VCO covers the frequency range of 23.75~24.8 GHz. The simulated phase noise of center frequency is -102.6 dBc/Hz at 1 MHz offset frequency. The VCO consumes 10.4 mW DC power under 1.8 V supply voltage. The figure of merit of the VCO is -179.8 after compensating.