A 7.3–9.5-GHz Cryogenic LNA Based on Passive Noise Cancellation for Qubit State Readout

A cryogenic low-voltage, broadband low-noise amplifier(LNA) has been designed for qubit state readout systems. The proposed LNA utilizes passive components for noise cancellation. A tri-coupled transformer is utilized to simultaneously achieve broadband input impedance matching and noise matching. Additionally, it incorporates capacitive feedback and an in-phase transformer to effectively cancel noise. Implemented in 28-nm bulk CMOS technology and verified at 10 K, the LNA achieves a maximum gain of 26.7 dB, a −3-dB bandwidth of 2.2 GHz, a lowest noise temperature (NT) of 25 K, a power consumption of 4.05 mW at 0.6-V supply voltage, and a figure of merit (FoM) of 0.12 dB/mW/ph, which is comparable with the recent works.