A very low-power quadrature VCO with back-gate coupling

A new quadrature voltage-controlled oscillator (QVCO) topology is proposed where the back-gates of the core transistors are used as coupling terminals. The use of back-gates reduces the power dissipation and removes the additional noise contributions compare to the conventional coupling transistor based topology. The advantages of the proposed QVCO topology in comparison with prior works are exploited based on simulation. A QVCO based on the proposed topology with additional design ideas has been implemented using a 0.18-/spl mu/m triple-well technology for 1 GHz-band operation, and measurement shows the phase noise of -120 dBc/Hz at 1-MHz offset with output power of 2.5 dBm, while dissipating only 3 mA for the whole QVCO from 1.8-V supply.