Continuous rounds of quantum error correction (QEC) are essential to achieve faulttolerant quantum computers (QCs). In each QEC cycle, thousands of ancilla quantum bits (qubits) must be read out faster than the qubits' decoherence time (<<T2∗~120μs for spin qubits). To address this urgent need, several CMOS receivers operating at cryogenic temperatures (cryo-CMOS RXs) have recently been introduced for gate-based [1] and RF reflectometry [2] readout of spin qubits, as well as transmons' dispersive readout [3]. However, they have a few shortcomings. First, due to the temperatureindependent shot noise of transistors in nanometer CMOS technology [4], their measured noise temperature (TN) is limited to 40K, thus degrading qubit readout fidelity. Second, due to their large TN, prior art showed either only the electrical performance of their chips by applying a relatively large (i.e., -85dBm [2]) modulated signal directly to the RX input [2,3] or offered limited qubit measurements by exploiting a HEMT amplifier prior to the RX [1]. Those issues hinder future monolithic integration between solid-state qubits and readout electronics. This work advances the prior art by (1) introducing a wideband passive amplification circuit at the RX front-end to minimize the shot noise contribution of the active devices, lowering prior art TN by ~2.7x; (2) demonstrating the RX performance in an RF-reflectometry qubit readout scheme without using off-the-shelf LNA prior to the RX.

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Recently, the so-called sub-6GHz band of the 5G new radio (NR) has been extended to 7.125GHz to address the relentless customer demand for higher data-rate communication. This demands a new design approach for the local area base-station (LA-BS) receivers (RXs) to cover a wide operating frequency range of 0.41 to 7.125GHz. Moreover, for NR bands above 3GHz, the maximum RF bandwidth (BW) is as high as 400MHz, in which a -35dBm modulated in-band (IB) blocker can be present. These impose stringent BW and IB linearity requirements for the baseband amplifiers in the LA-BS receivers. In addition to IB interferences, a -15dBm continuous-wave (CW) out-of-band (OOB) close-in blocker can also be present at 60MHz offset frequency from the passband edges, thus demanding a highly selective RX. Finally, the blocker 1dB compression point (B1textdB) becomes a key parameter for local area co-location applications in which the power of the far-out OOB blocker can be as large as -4dBm.

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This article presents a wideband blocker tolerant receiver (RX) for fifth-generation (5G) user equipment applications. Two programmable zeros around the channel bandwidth are introduced to sufficiently suppress the close-in blockers of 5G applications. Since the effect of zeros gradually diminishes at larger out-of-band offset frequencies, an auxiliary current-sinking path is also introduced to reduce the RX input impedance at far-out offset frequencies. Moreover, a simple second-order transimpedance amplifier (TIA) is adopted to enhance the proposed RX selectivity. The utilized TIA synthesizes two complex conjugate poles to achieve a flat gain response and -40 dB/dec roll-off. A 40-nm CMOS RX prototype occupies 1.15mm2 and consumes 84-140mW from a 1.3-V supply voltage over the 0.5-3-GHz operating frequency range. The RX achieves a 160-MHz RF bandwidth, 2.6-4.2-dB noise figure, a -0.3-dBm blocker 1-dB compression point (B1dB), and an out-of-band third-order intercept point (IIP3) of 22.5 dBm. As a test case, using the 3GPP standard, a -15-dBm continuous wave (CW) close-in out-of-band blocker located at 85-MHz offset from the passband edges is applied to the RX. Thanks to the receiver's high selectivity, the RX achieves 100% throughput while detecting 100-MS/s quadrature phase shift keying (QPSK) signal with 16 dB higher power than the reference sensitivity.

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By introducing three different techniques, this article, for the first time, presents a wideband highly linear receiver (RX) capable of handling blocking scenarios in fifth-generation (5G) microcell base station applications. First, a parallel preselect filter is introduced to satisfy the base station co-location blocking requirements. Next, a combination of third-order RF and baseband (BB) filters is adopted to attenuate close-in blockers by a -120 dB/dec roll-off. Finally, a translational feedback network is proposed to reduce the in-band gain ripple to below 0.5 dB and provide better than -19 dB input matching. Fabricated in the 40-nm CMOS technology, the proposed RX occupies a core area of 0.8 mm2 and consumes 108-176 mW from a 1.3 V supply over the RX's 0.5-3-GHz operating frequency. It achieves a 3-dB bandwidth of 150 MHz and a noise figure (NF) of 2.6-3.9 dB over the RX frequency range. Activating the parallel preselect filter degrades the NF by as little as 1.2 dB in the worst case. The RX shows a ≥q 97.5% throughput when receiving a 100-MS/s quadrature phase shift keying (QPSK) signal with 7.5-dB SNR and achieves a -9.7 dB error vector magnitude (EVM) while facing a -15 dBm continuous-wave (CW) blocker only 20 MHz away from the desired 100-MS/s QPSK signal with 12.3-dB SNR, thus satisfying the 3rd generation partnership project (3GPP) requirements with sufficient margin.

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Recent sub-6GHz receivers (RXs) attempted to realize RF channel selection at the RX input for suppressing large close-in blockers. Although mixer-first RXs can achieve sharp RF filtering and good out-of-band (OOB) linearity, they suffer from large noise figure (NF) and high LO leakage [1] [2]. Alternatively, [3]–[5] exploited an N-path notch filter around an LNTA to simultaneously achieve low NF and a moderate channel selection at the RX input. However, their OOB IIP3 and blocker 1dB compression point (B1dS) are at least 10dB worse than the mixer-first RXs. This paper proposes an LNTA-based RX that shows a similar OOB linearity as prior art mixer-first RXs without sacrificing NF. This is achieved by (1) adding a parallel preselect filter at the RX input to improve the RF selectivity and achieve +6dBm B1dB; (2) proposing third-order RF and baseband filters to attenuate close-in blockers by a 120dB/dec roll-off; (3) introducing a feedback network to reduce the in-band (IB) gain fluctuations to <0.5dB.@en

The introduction of the fifth-generation (5G) New Radio (NR) standard has imposed several challenges in the design of sub-6GHz receivers (RX). Firstly, the maximum channel bandwidth(2BW) increases to 100MHz, while a -15dBm continuous-wave (CW) blocker can be located only \Delta f=85MHz away from the desired band edge. Such a small \Delta f/BW(\sim2) places a stringent linearity requirement on an RX, thus demanding the use of higher-order filtering. Secondly, in-band (IB) linearity also becomes critical, since the band of interest may contain many signals resulting from carrier aggregation and digital beamforming 0peration. Finally, a sub-3dB noise Figure (NF) is required to achieve the highest possible link budget, which allows to maximize the spectral efficiency and data rate.

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