Analysis and design of mm-wave detectors in SiGe SoC radiometers for spaceborne observations of solar flares

This paper presents a comparative study of detector circuit topologies for the implementation of Ka-band system-on-chip (SoC) Dicke radiometer for spaceborne observation of solar flares. In particular, common-emitter (CE), common-collector (CC), common-base (CB), Darlington and cascode detector circuit topologies are studied and compared in terms of responsivity (R) and noise equivalent power (NEP). The study is carried out in a commercial SiGe-BiCMOS 0.13μm technology currently under space evaluations. The results show that the CE topology is the most suitable topology in the Ka-band. In detail, it exhibits a responsivity of about 480 kV/W and NEP of about 150 fW/√Hz. Last, the system analysis and design of the SoC radiometer incorporating the CE detector topology is carried out. The results show that the targeted resolution of 0.7 K (1 solar flux unit) can be achieved with reasonable integration time (48 ms) also considering the insertion losses of the antenna switch.