A low power 10 GHz current reused VCO using negative resistance enhancement technique

Design and Analysis of a 0.4V 1.08mW 12GHz High-Performance VCO in 0.18μm CMOS (Invited Paper)

“…Combine 2and 3, the transfer function considering the V o and V i of the active device M 2 can be formulated in (4). From (4), it is observed that the Vo/Vi can be increased by utilizing a small capacitance ratio (C DS /C S ).…”

“…This leads to a capacitance ratio of 1/4. According to (4), it also predicts that a small capacitance ratio (C DS /C S ) enhances Vo/Vi and VCO loop gain. From Fig.7, it is indicated that the differential voltage swings at the tank with and without capacitive-divided feedbacks are 736 mV pp and 230 mV pp , respectively.…”

“…This dc level shifter, however, required 1.8V high supply voltage and 8.1mW large core power. For increasing negative resistance in a VCO, a method of applying additional cross-coupled pair at the VCO core was described in [4]. Although this additional cross-coupled pair can relax the start up condition, however, it raised the total power dissipation up to 16.27 mW.…”