An Interference Suppression Technique for Millimeter-Wave LC VCOs Using a Multiport Coupled Inductor

A 4-port inductor structure with improved electromagnetic(EM) interference suppression for mm-wave LC VCOs is proposed in this brief. Two single turn inductors are coupled to form a 4-port 8-shaped structure which greatly suppresses the EM interference from neighboring aggressors. Since two LC tanks are coupled to form a dual-core oscillator, it exhibits two modes of oscillation. Mode-suppression resistors are connected between 2 closely spaced terminals of the 4-port coupled inductor to suppress the unwanted mode of oscillation. This makes the dual-core VCO robust and free from mode ambiguities. A 24-to-30 GHz LC VCO is built using the proposed 8-shaped 4-port coupled inductor in a 7nm FinFet process for a multi-lane 100G wireline application. The VCO exhibits a simulated phase noise of −102 dBc/Hz at 1MHz at 28 GHz consuming only 4.6 mW and exhibits up to 23 dB better interference suppression when compared to a conventional single-core LC VCO.