Reversible operation of a CMOS Colpitts VCO as a W-band passive detector and energy harvesting

An innovative topology for detecting and harvesting energy in the W-band has been realized in 90 nm CMOS process. The circuit uses a differential Colpitts topology in reverse mode to convert an input W-band signal into a DC voltage, current or power output. The circuit achieves a voltage responsivity of 2.1 kV/W at 95 GHz, current responsivity of 2.9 A/W at 99 GHz and NEP of 11.9 pW√Hz without DC power consumption. In power harvesting mode an efficiency of 5% is achieved for an 11.4 dBm at 99 GHz input signal. The design occupies only 0.15 mm2 including pads.