Subharmonic 245 GHz SiGe receiver with antenna

A subharmonic receiver (RX) for sensing applications in the 245 GHz ISM band is presented. The RX consists of a differential LNA, a 122 GHz push-push VCO with 1/64 divider, a LO-buffer, a 90° differential hybrid, an active subharmonic mixer, and an on-chip antenna. The VCO frequency is tunable by an external PLL in the range from 118 GHz to 125 GHz. The RX is fabricated in 0.13 μm SiGe:C BiCMOS technology with ft/fmax of 300GHz/500GHz. Its conversion gain is 18 dB at 245 GHz, and the estimated noise figure is 18 dB. The 3-dB bandwidth reaches from 244 GHz to 250 GHz. The input 1-dB compression point is at -25 dBm. The conversion gain of RX with integrated antenna was estimated using a quasi-optical setup. The RX power dissipation of 0.6 W requires an effective thermal sink for the mounted RX-chip to avoid degradation of its conversion gain.