A 40‐ GH z hybrid class‐ AB /class‐ B CMOS VCO with a current‐combining transformer

A 40‐GHz hybrid class‐AB/class‐B CMOS VCO with a current‐combining transformer (CCT) using a 65‐nm RF CMOS process is presented. The hybrid class‐AB/class‐B configuration is adapted to two cross‐coupled pairs to lower the power consumption while maintaining the phase noise performance. As a simple coupling network between two cross‐coupled pairs with different bias conditions, the CCT performs the roles of a high Q‐factor resonator, a large impedance transformer, and a buffer without additional circuitry. The VCO operates at 38.15–40 GHz with power consumption in the range of 11–13 mW. The measured phase noise at a 1‐MHz offset from the 40 GHz carrier is −117.1 dBc/Hz with a 1.0 V supply voltage. The proposed power oscillator achieves an FOM T value of −191.3 dBc/Hz.