A Subharmonic Receiver in SiGe Technology for 122 $~$ GHz Sensor Applications

The iterative design of an integrated subharmonic receiver for 120-127 GHz is presented. The receiver consists of a single-ended low-noise amplifier (LNA), a push-push voltage-controlled oscillator (VCO) with 1/32 divider, a polyphase filter, and a subharmonic mixer. The receiver is fabricated in SiGe:C BiCMOS technology with fT/f_max of 255 GHz/315 GHz. In the first design the differential down-conversion gain of the receiver is 25 dB at 127 GHz, and the corresponding noise figure (NF) is 11 dB. The 3 dB bandwidth reaches from 125 GHz to 129 GHz. The input 1 dB compression point is at - 40 dBm. The receiver draws 139 mA from a supply voltage of 3.3 V. A subsequent design demonstrates 31 dB differential gain at 122 GHz, and 11 dB NF. The 3 dB bandwidth is from 121 GHz to 124 GHz. The receiver has a NF of 8 dB for 3 GHz IF frequency due to integrated RF bandpass-filtering. It is realized by the lower NF of the LNA, and the LNA itself.