A High-Linearity Down-Conversion Mixer with Modified Transconductance Stage about 120 GHz

This work proposes a high-linearity down-conversion mixer with a modified transconductance stage of Gilbert cell at about 120 GHz in a 55-nm CMOS process. The mixer attains at least 2 dBm input-referred 1 dB compression point (IP1dB) by adopting Gilbert cell with multiple gate transistors (MGTR) technology, source degeneration technology, and drain-gate parallel inductors. The improvement of traditional MGTR technology enables it to be applied in a sub-terahertz band and still has a certain effect on linearity improvement. Compared with other MGTR manufacturing, the improvement of linearity is no longer sensitive to bias voltage, which is helpful for practical applications. The measurement results show that the proposed mixer exhibits good linearity performance in a sub-terahertz band, and the frequency conversion loss is within an acceptable range. The RF, LO, and IF ports are measured to match 90–123 GHz,50–67 GHz, and 52–67 GHz, respectively. Under the consideration of a low-cost design, the DC power consumption of the proposed mixer is only 8.2 mW. The core chip occupies only 0.28 × 0.28 mm. This is the first application of MGTR mixers in a sub-terahertz band.