Ultracompact Inductorless Noise-Canceling LNAs in 40-nm CMOS Achieving 2.2-K Noise Temperature for Qubit Readout

• Published in: IEEE transactions on microwave theory and techniques 2024-04, Vol.72 (4), p.1-11
• Main Authors: Chaubey, Mahesh Kumar, Liu, Yeke, Chang, Yin-Cheng, Wu, Po-Chang, Tsai, Hann-Huei, Hsu, Shawn S. H.
• Format: Article
• Language: English
• Subjects: Amplifiers; CMOS; Cryoforming; cryogenic; Cryogenics; Gain; Impedance matching; inductorless; Input impedance; low-noise amplifier (LNA); noise canceling (NC); Noise levels; Noise measurement; Noise temperature; Power consumption; quantum computing; Qubit; Radio frequency; Receivers; Resistors; Room temperature
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2024.3356653

This article presents two ultracompact inductorless low-noise amplifiers (LNAs) in 40-nm CMOS for cryogenic qubit readout. Both LNAs utilize an inverter-based input stage as the main amplifier, and LNA-I and LNA-II employ a complementary and common-source (CS) stage, respectively, as the auxiliary amplifier for achieving noise canceling (NC). LNA-I also incorporates self-forward body bias (SFBB) to counter V _{\text{th}} reduction and improve r _{\text{out}} during cryogenic operation, while LNA-II uses source-follower feedback(SFFB) to enhance gain and noise figures (NFs) without compromising input impedance matching. At room temperature (RT), LNA-I achieves a measured gain ( S _{{21}} ) of 25.6 dB and a minimum NF of 0.63 dB at 2 GHz. At 4 K, it demonstrates a measured gain of 29 dB and a minimum NF of 0.033 dB (corresponding to a noise temperature T _{{N}} of 2.2 K), along with a 3-dB bandwidth f _{\text{3\,dB}} from 10 MHz to 3 GHz, while consuming 19.4 mW. LNA-II achieves a measured gain of 27 dB and a minimum NF of 1.16 dB at 0.5 GHz at RT. At 4 K, it demonstrates a measured gain of 30.2 dB and a minimum NF of 0.29 dB ( T _{{N}} of 20 K), accompanied by a f _{\text{3\,dB}} from 20 MHz to 4 GHz and with a total power consumption of 10.8 mW. The circuit only occupies an active area of 0.018 and 0.0072 mm ^{{2}} for LNA-I and LNA-II, respectively.