Reduction of VCO phase noise through forward substrate biasing of switched MOSFETs

A reduction of close to carrier phase noise of a 14 GHz PMOS VCO is presented by forward substrate biasing the MOSFETs providing the oscillation in the VCO. This finding is explained by the physical effect of significantly reduced 1/f noise in transistors operated under large signal excitation and forward substrate bias. Measurements of MOSFET 1/f noise under switched gate bias condition and VCO phase noise are presented to explain the dependency between reduced 1/f noise and reduced VCO phase noise with forward substrate bias.