This paper proposes two fully passive techniques to reduce the supply sensitivity of an LC oscillator. An RC low-pass filter is employed to reduce the supply sensitivity of coarse-tuning switched capacitors stemming from code-dependent parasitic capacitance. To cancel the remaining supply sensitivity, the supply variations are scaled and coupled to polarity-switchable varactor pairs, which are introduced in the resonator to provide a frequency tuning gain that is reverse to the supply sensitivity. A programmable capacitive divider is used to scale the supply variations by a proper ratio. The proposed techniques are applied in a 5.83-6.99 GHz class-B LC oscillator. Prototyped in 65-nm CMOS, the oscillator occupies 0.24 mm ² and consumes 6.8 mW from 1 V. With supply perturbations in the 0.1-50 MHz frequency range, the measured reduction of the supply sensitivity is 20-46.2 dB, which is the highest reported over a wide frequency range. Benefiting from the fully passive implementation, the proposed techniques do not consume extra power or degrade the phase noise.

Parasitic coupling between the building blocks within a fractional- N phase-locked loop (PLL) can result in noticeable spurs in its output spectrum, thus affecting the PLL’s usability in ultralow jitter applications. In this article, we focus on a chief contributor—“self-interference” caused by coupling from the PLL’s frequency-reference (FREF) clock buffer to the RF oscillator, while exploiting the fact that the resulting phase-disturbance pattern: 1) exhibits a sinusoidal shape and 2) is synchronized with the PLL’s output clock phase. Accordingly, we propose a digitally intensive pattern-aware approach to suppress the fundamental fractional spur raised by this self-interference mechanism. The proposed technique is applied to a fabricated digital PLL chip and reduces the worst spur level by 13 dB, thus proving its effectiveness.

This article introduces a low-jitter low-spur fractional-N phase-locked loop (PLL) adopting a new concept of a time-mode arithmetic unit (TAU) for phase error extraction. The TAU is a time-signal processor that calculates the weighted sum of input time offsets. It processes two inputs - the period of a digitally controlled oscillator (DCO) and the instantaneous time offset between the DCO and reference clock edges - and then extracts the DCO phase error by calculating their weighted sum. The prototype, implemented in 40-nm CMOS, achieves 182-fs rms jitter with 3.5-mW power consumption. In a near-integer channel, it shows the worst fractional spur below -59 dBc. Under considerable supply or temperature variations, the worst spur still remains below -51.7 dBc without any background calibration tracking.

Over the past decade, significant progress in quantum technologies has been made, and hence, engineering of these systems has become an important research area. Many researchers have become interested in studying ways in which classical integrated circuits can be used to complement quantum mechanical systems, enabling more compact, performant, and/or extensible systems than would be otherwise feasible. In this article - written by a consortium of early contributors to the field - we provide a review of some of the early integrated circuits for the quantum information sciences. Complementary metal - oxide semiconductor (CMOS) and bipolar CMOS (BiCMOS) integrated circuits for nuclear magnetic resonance, nitrogen-vacancy-based magnetometry, trapped-ion-based quantum computing, superconductor-based quantum computing, and quantum-dot-based quantum computing are described. In each case, the basic technological requirements are presented before describing proof-of-concept integrated circuits. We conclude by summarizing some of the many open research areas in the quantum information sciences for CMOS designers.

In this article, we present a low-power digital phase-locked loop (PLL)-based phase modulator targeting low error vector magnitude (EVM). We introduce a new non-uniform clock compensation (NUCC) scheme to tackle an EVM degradation resulting from the beneficial use of a time-varying sampling clock that is re-timed to the phase-modulated carrier. We also employ a phase-domain digital predistortion (DPD) to combat the intrinsic non-linearity of an LC-type digitally controlled oscillator (DCO), thus avoiding the complications of frequency-dependent calibrations. The prototype, implemented in 40-nm CMOS, modulates the carrier in the range of 2.7-3.9 GHz from a 40-MHz reference. The measured EVM is -47 dB for a 60-Mb/s 64-PSK modulation under the case that the phase-modulated output is frequency-divided by K=8 , i.e., when the DCO exhibits the most significant non-linearity due to the large fractional FM bandwidth. When K=8 or 4, the measured EVM remains below -43 dB across the carrier-frequency tuning range and without re-calibrating the DCO non-linearity.

The grand challenge of scaling up quantum computers requires a full-stack architectural standpoint. In this position paper, we will present the vision of a new generation of scalable quantum computing architectures featuring distributed quantum cores (Qcores) interconnected via quantum-coherent qubit state transfer links and orchestrated via an integrated wireless interconnect.

In this article, we present a 4.5-5.1-GHz fractional-N digitally intensive phase-locked loop (DPLL) capable of maintaining its performance in face of a large supply ripple, thus enabling a direct connection to a switched-mode dc-dc converter. Supply pushing of its inductor-capacitor (LC) oscillator is suppressed by properly replicating the supply ripple onto the gate of its tail current transistor, while the optimum replication gain is determined by a new on- chip calibration loop tolerant of supply variations. A proposed configuration of cascading a supply-insensitive slope generator with an output of a current digital-to-analog converter (DAC) linearly converts the phase error timing into a corresponding voltage, which is then quantized by a successive approximation register (SAR) analog-to-digital converter (ADC) to generate a digital phase error. We also introduce a low-power ripple pattern estimation and cancellation algorithm to remove the phase error component due to the supply-induced delay variations of loop components. Implemented in 40-nm CMOS, the DPLL prototype achieves the performance of 428-fs rms jitter, <-55-dBc fractional spur, and <-54-dBc maximum spur while consuming 3.25 mW and being subjugated to a sinusoidal or sawtooth supply ripple of 50 mVpp at 50-MHz reference divided by 3, 6, or 12.

We present a broadband digital PLL (DPLL)-based phase modulator supporting wide frequency modulation (FM) bandwidth (BW). It compensates for the EVM degradation due to the non-uniform period of the retimed updating clock and shortens the nonlinearity calibration time of the digitally controlled oscillator (DCO) with a phase-domain digital pre-distortion (DPD) and an encoding-assisted (EA)-LMS calibration. While generating a 10MHz 64-PSK signal, the prototype can achieve -46dB EVM with less than one-tenth of the calibration samples (time) required by the prior art.

In this article, we introduce a fractional-N all-digital phase-locked loop (ADPLL) architecture based on a single LC-tank, featuring an ultra-wide tuning range (TR) and optimized for ultra-low area in 10-nm FinFET CMOS. Underpinned by excellent switches in the FinFET technology, a high turn-on/off capacitance ratio of LC-tank switched capacitors, in addition to an adjustable magnetic coupling technique, yields almost an octave TR from 10.8 to 19.3GHz. A new method to compensate for the tracking-bank resolution can maintain its quantization noise level over this wide TR. A new scheme is adopted to overcome the metastability resolution problem in a fractional-N ADPLL operation. A low-complexity TDC gain estimator reduces the digital core area by progressive averaging and time-division multiplexing. Among the published fractional-N PLLs with an area smaller than 0.1mm2, this work achieves an rms jitter of 725fs in an internal fractional-N mode of ADPLL's phase detector (2.7-4.825GHz) yielding the best overall jitter figure-of-merit (FOM) of -232dB. This topology features small area (0.034mm2), wide TR (56.5%) and good supply noise rejection (1.8%/V), resulting in FOMs with normalized TR (FOMT) of -247dB, and normalized TR and area (FOMTA) of -262dB.

Millimeter-wave (mm-wave) frequency synthesizers in complementary metal oxide-semiconductor (CMOS) suffer from poor phase noise (PN), limited tuning range (TR) and high-power consumption. They are the key subsystems that typically limit the performance of mm-wave transceivers. This chapter presents a new architecture for mm-wave frequency synthesis that improves its PN performance and power efficiency. Various different techniques are introduced and demonstrated in a 60-GHz fractional-N all-digital phase-locked loop (ADPLL).

This paper presents a digitally controlled frequency generator for dual frequency-band radar system that is optimized for 16 nm FinFET CMOS. It is based on a 21% wide tuning range,fine-resolution DCO with only switchable metal capacitors. A third-harmonic boosting DCO simultaneously generates 22.5-28 GHz and sufficiently strong 68-84 GHz signals to satisfy short-range radar (SRR) and medium/long range radar (M/LRR) requirements. The 20.2 mW DCO emits -97 dBc/Hz at 1 MHz offset from 77 GHz,while fully satisfying metal density rules. It occupies 0.07 mm²,thus demonstrating both 43% power and 47% area reductions. The phase noise and FoM_T (figure-of-merit with tuning range) are improved by 1.8 dB and 0.2 dB,respectively,compared to state-of-the-art.

This article proposes a power-efficient highly linear capacitor-array-based digital-to-time converter (DTC) using a charge redistribution constant-slope approach. A fringe-capacitor-based digital-to-analog converter (C-DAC) array is used to regulate the starting supply voltage of the constant discharging slope fed to a fixed-threshold comparator. The DTC operation mechanism is analyzed and design tradeoffs are investigated. The proposed DTC consumes merely 31 μW from a 1-V supply when clocked at 40 MHz, while achieving a fine resolution of 148 fs over a 9-bit range. The measured differential nonlinearity (DNL) and integral nonlinearity (INL) are 0.96/1.07 LSB.

This paper proposes a mm-wave quadrature frequency generator using injection-locked harmonic extractors (HEs) incorporated with quadrature class-F oscillators. While maintaining high output levels at 28 GHz, the utilization of injection locking technique improves the effective quality ($Q$)-factor and helps to achieve a fundamental harmonic suppression of 60 dB. This results in an FoM of the entire frequency generation system reaching -184 dB. The consideration of quadrature phase mismatch induced by electromagnetic coupling between quadrature buffers is also discussed.

In this paper, we propose a method to suppress supply pushing of an LC oscillator such that it may directly operate from a switched-mode dc-dc converter generating fairly large ripples. A ripple replication block (RRB) generates an amplified ripple replica at the gate terminal of the tail current source to stabilize the oscillator's tail current and thus its oscillating amplitude. The parasitic capacitance of the active devices and correspondingly the oscillation frequency are stabilized in turn. A calibration loop is also integrated on-chip to automatically set the optimum replication gain that minimizes the variation of the oscillation amplitude. A 4.9-5.6-GHz oscillator is realized in 40-nm CMOS and occupies 0.23 mm&#x00B2; while consuming 0.8-1.3 mW across the tuning range (TR). The supply pushing is improved to &lt;1 MHz/V resulting in a low &lt;-49-dBc spur due to 0.5-12-MHz sinusoidal supply ripples as large as 50 mVpp. We experimentally verify the effectiveness of the proposed technique also in face of saw-tooth, multi-tone, and modulated supply ripples.

In this paper, we propose a 60-GHz fractional-N digital frequency synthesizer aimed at reducing its phase noise (PN) at both the flicker (1/f ³ ) and thermal (1/f ² ) regions while minimizing its power consumption. The digitally controlled oscillator (DCO) fundamentally resonates at 20 GHz and co-generates a strong third harmonic at 60 GHz which is extracted to the output while canceling the 20-GHz fundamental. The latter component is fed back to the frequency dividers in an all-digital phase-locked loop for phase detection, which comprises a pair of digital-to-time and time-to-digital converters with dithering to attenuate fractional spurs. The mechanism of flicker noise upconversion to 1/f ³ PN in the DCO is investigated, and a reduction technique is proposed. The 28-nm CMOS prototype achieves 213-277-fs rms jitter in the 57.5-67.2-GHz tuning range while consuming only 40 mW. The DCO flicker PN corner is record low at 300-400 kHz.

In this paper, we investigate an impact of voltage supply scaling on power consumption and performance of a new class of wireless receivers (RX) for Internet-of-Things (IoT) applications: a discrete-time (DT) superheterodyne architecture realized in nanoscale CMOS using inverter-based gm and switched capacitors. The power supply is partitioned into three separate domains: RF, intermediate frequency (IF) processing, and clocking, which allows them to be independently regulated to assess their respective impact. The DT-RX maintains its functionality, albeit with some acceptable loss of performance, when the core supplies are varied by as much as an octave, i.e., from the nominal 1.1 V down to 0.55V. The DT-RX IC is then connected to a switched-capacitor based voltage doubler array on a companion IC die such that the DT-RX can be powered at the octave range of 0.275-0.55 V from an energy harvester. The sensitivity at the doubler's 0.275/0.55 V input is -85/-95 dBm while consuming 1.0/2.4mW. Both ICs are implemented in TSMC 28-nm LP CMOS.