120nm 1.2V low noise VCO with over seven octave tuning range

Inverter based voltage controlled oscillators are a fundamental building block in analogue integrated circuit design and enjoy a more compact size and wider tuning range than their inductor capacitor counterparts. In some applications an ultra wide tuning range is desired and this can be difficult to achieve when combined with the requirement for good phase noise. This paper presents a double feedback dual inverter delay cell that demonstrates a significantly wider tuning range than previously reported designs whilst maintaining excellent phase noise performance. A key contribution to the work is the fabrication of a 120nm 1.2V prototype chip with measured results confirming a tuning range of over seven octaves.