Background: Design of an ultra-low voltage 0.28V CMOS VCO based on current reused
topology for low power application is presented. The high performance of ultra-low voltage operation is
achieved by way of the transformer feedback and body bias technique.
Methods: The total power dissipation can be achieved as low as 260µW, while VDD1 and VDD2 are
both 0.28V. The swing of output signal above the VDD supply voltage is improved by transformer
feedback loop. The tuning range of proposed VCO is from 2 to 2.3 GHz under 0.28V supply voltage
which PMOS and NMOS transistor with the threshold voltage is around 0.52V and -0.52V,
Result: The measurement of phase noise is -106.5dBc/Hz at 1MHz offset from the 2.26GHz frequency
carrier at 0.28V.
Conclusion: The chip is implemented with 0.18μm CMOS process and its figure of merit is -