A 196-to-254-GHz Slot-Array Coupled Detector Using Process-Invariant Pseudo Resistor Technique

This letter presents a compact slot-array coupled terahertz (THz) detector achieving a high baseband responsivity of 10 MV/W. The core circuit of the THz detector is based on the principle of square-law detection and realized by a common-source structure. In order to reduce the impact of process variation, a novel bias scheme for pseudo resistor (PR) is proposed to stabilize the baseband bandwidth. A slot-array coupler is employed to extract the THz signal from waveguide for measurement requirement. Fabricated in a 65-nm CMOS process, the proposed detector demonstrates effective detection from 196 to 254 GHz with 25.8% fractional bandwidth. The measured responsivity and noise equivalent power (NEP) are 1.6 kV/W and 39 pW/Hz^0.5, respectively. Together with the cascaded baseband amplifier, the maximum baseband responsivity of 10 MV/W is achieved.