A tail-current modulated VCO with adaptive-bias scheme

This paper proposes a tail-current modulated VCO with adaptive-bias scheme. The proposed adaptive-bias scheme ensures robust startup conditions for the tail-feedback VCO. A tail-feedback VCO using the proposed scheme is implemented in a 0.18-μm CMOS process. The measured phase noise is -119.3dBc/Hz at 1MHz offset with a power dissipation of 6.8mW at 4.6GHz.