A 90-to 115-GHz superheterodyne receiver front-end for W-band imaging system in 28-nm complementary metal-oxide-semiconductor

In this paper, a broadband superheterodyne receiver (RX) front-end for millimeter-wave (mm-Wave) imaging radar is presented. Realized in 28-nm CMOS technology, the proposed RX incorporates a wideband low-noise amplifier (LNA), double-balanced passive mixers for the dual down-conversion, a differential power divider, a differential intermediate frequency filters, a current-mode-logic divider-by-2, and a local oscillator buffers. Wideband technique and layout optimization are taken into consideration in the RX. A four-stage LNA is devised to realize the high gain and low noise figure (NF) with a common-gate input stage and three pseudodifferential common-source stages. Optimized transistor layout and capacitor neutralization technique are developed to improve gain and noise performance. Transformer-based matching networks with the peak-staggered technique are adopted in the LNA to achieve a flatter gain response with a wider bandwidth (BW). The passive double-balanced mixers are implemented with a highly symmetrical layout for broadband down-conversion. Simulation results show that the mm-Wave RX front-end exhibits a BW ranging from 90 to 115 GHz. The simulated NF of our RX is 4.7 dB at 86 GHz. With a supply voltage of 1 V, the presented RX consumes 88.2-mW power and occupies a chip size of 1.6 x 0.5 mm(2) including all the testing pads. The proposed RX is suitable for W-band imaging systems.