Low-voltage, low-power and low phase noise 2.4 GHz VCO for medical wireless telemetry

The design and simulation results of low-voltage, and low-power LC VCO is presented. The oscillator is used for portable wireless telemetry devices that operate under unusual supply voltage and power requirements. The VCO is designed to operate in the 2.4 GHz industrial scientific and medical (ISM) band. The novelty of this design is the low supply voltage which is equal to 0.4 V, about 100 mV below the threshold voltage of the MOSFETs used, and hence, the MOSFETs used are biased to operate in the sub-threshold region. The effect of the common-source inductor is also emphasized from the power consumption point of view. The VCO was simulated using CMOS 0.18 μm process. The simulated performance characteristics are: power consumption of 41 μW; phase noise of -123 dBc/Hz, -129.5 dBc/Hz and -133.1 dBc/Hz at offsets of 1 MHz, 2 MHz and 3 MHz, respectively; frequency tuning range of 18%.