This article presents a cryogenic CMOS receiver operating across 4.7–7.9 GHz for frequency-division multiplexing (FDM) quantum state readout. The designed receiver employs a double quadrature (DQ) architecture and a hybrid poly-phase filter (PPF) is proposed to achieve an impressive image rejection ratio (IRR) to meet the 99.99% higher fidelity requirements in quantum error correction (QEC). In addition, gain tuning at different stages of the low noise amplifier (LNA) facilitates a broadband gain and flatness, while the subsequent receiver chains of a broadband mixer and an improved four-input intermediate frequency amplifier (IF-AMP) provide further gain compensation. Fabricated with a standard 55-nm CMOS technology, the LNA achieves a measured power gain of 27.4 dB, with a −3-dB bandwidth (BW) of 5.2 GHz at 6 K. The measured cryogenic noise figure (NF) ranges from 0.79 to 1 dB consuming merely 5.5 mW from a 1.2-V supply. Overall receiver measurements demonstrate a peak gain of 48.2 dB, a −5-dB flatness of 3.2 GHz, and an IRR that exceeds 40 dB at 6 K. These results demonstrate the receiver’s capacity for high-fidelity qubits’ state readout.

This work introduces a broadband cryogenic receiver for scalable multiplexed readout of qubits. The receiver utilizes a double quadrature architecture with amplitude and phase error suppression. The hybrid poly-phase filter (PPF) is applied in the architecture to further reduce the input amplitude and phase errors at the radio frequency (RF) end, enhancing the circuit's overall error vector magnitude (EVM). To address the issue of wide bandwidth (BW) for qubit expansion, a low noise amplifier (LNA) with broadband input and noise matching and an improved four-input intermediate frequency amplifier (IF-AMP) with a resistance feedback structure are proposed, achieving a broadband gain response with high flatness. The chip has been designed in standard 55 nm CMOS technology. The LNA achieves a measured power gain of 27.4 dB at 5 GHz with a -3 dB BW of 5.2 GHz at 6 K. Across the entire band of interest, the measured noise figure (NF) deviates by just 0.15 dB from the minimum noise figure (NFmin) and less than 2 dB at 300K, while the measured cryogenic NF falls within the range of 0.79-1 dB. The LNA consumes only 5.5 mW from a 1.2 V supply. Simulation results of the designed receiver indicate that it delivers an average gain of 49.5 dB with a -3 dB BW of 2.4 GHz and an image rejection ratio (IRR) exceeding 40 dB at 300 K.

This paper presents a 320×240 indirect time of flight (I-ToF) image sensor with 5.6μm×5.6μm 2-Tap pixel in 110nm process. The readout channel offset cancellation and nonlinearity suppression techniques are proposed to achieve high-precision detection. The measured relative precision is 1% at a 5m target distance and non-linearity is below 1.02%. The chip also integrates LVDS and I2C interface for data transmission and Laser control. This work effectively improved the ranging accuracy with a simple method.