Measured Phase Noise Research Articles

Analysis and Implementation of High-Q CT Inductor for Compact and Wide- Tuning Range Ku-Band VCO

This work presents a new structure of center tap (CT) inductor to improve the performance of Ku-band voltage-controlled oscillators (VCOs). Conventional CT inductor provided by the foundry suffers from a poor-quality (Q-) factor large area and low self-resonance frequency. These problems are solved by introducing a coupling structure. For the proposed CT inductor, despite its size is miniaturized by 51%, the Q-factor is increased by 41% in the frequency range of 5-30 GHz compared to a conventional CT inductor. The measured differential inductance and quality factor of the proposed inductor are 385 pH and 22 at 12 GHz. The proposed CT inductor is used to design a compact and wide-tuning-range VCO at Ku-band in 0.18-μm complementary metal-oxide-semiconductor (CMOS) technology, and this leads to 5.8 dB phase noise improvement compared to the use of a conventional CT inductor. The fabricated VCO has a compact core size of 140 μm × 400 μm only. The VCO chip oscillates from 11.7 to 13.7 GHz. The measured phase noise is -107.7 dBc/Hz at 1-MHz offset frequency at a carrier frequency of 13.7 GHz, and the dc power consumption of the VCO core is 4 mW which results in a figure of merit (FoM) normalized to the die area (FoMA) to be -197 dBc/Hz.

A 1.22 mW 2.4 GHz PLL Using a Single-Ring-Oscillator-Based Integrator With Background Frequency Calibration

A phase-locked loop (PLL) using a single-ring-oscillator-based integrator with background frequency calibration is presented. By introducing the single-ring-oscillator-based integrator, the in-band phase noise and the power efficiency of the PLL are improved. With background frequency calibration, it allows this PLL to tolerate process, supply voltage, and temperature variations. Moreover, the reference spur will be improved by using timing orthogonal scheme. This PLL is fabricated in 40-nm CMOS process which occupies an active area of 0.0011mm2. Its power consumption is 1.22mW from a 1V supply voltage. The measured phase noise is −100dBc/Hz, −108dBc/Hz and -110dBc/Hz at the offset frequencies of 100kHz, 1MHz, and 10MHz, respectively. The integrated root-mean-square jitter is 1.5psrms, and this PLL achieves a figure-of-merit of −235.6dB.

A Ku-Band Oscillator Utilizing Overtone Lithium Niobate RF-MEMS Resonator for 5G

This letter presents a 12.9-GHz silicon germanium (SiGe) Pierce oscillator using a third antisymmetric overtone in a lithium niobate (LiNbO3) resonator for 5G communications. Quarter-wave resonators are used to satisfy the Barkhausen oscillation conditions for the third overtone while suppressing the fundamental and higher order resonances. The oscillator achieves a measured phase noise of -70 and -111 dBc/Hz at 1 and 100-kHz offsets from a 12.9-GHz carrier while consuming 20 mW of dc power. The oscillator achieves a figure-of-merit of 200 dBc/Hz at 100-kHz offset, surpassing the state-of-the-art electromagnetic (EM) and overtone MEMS oscillators. The achieved oscillation frequency is the highest reported to date for an MEMS oscillator. The demonstrated performance shows the strong potential of microwave acoustic oscillators for 5G frequency synthesis. This work will enable low-power 5G transceivers featuring high speed, high sensitivity, and high selectivity in small form factors.

Towards a Scaleable 5G Fronthaul: Analog Radio-over-Fiber and Space Division Multiplexing

The introduction of millimeter wave (mm-wave) frequency bands for cellular communications with significantly larger bandwidths compared to their sub-6 GHz counterparts, the resulting densification of network deployments and the introduction of antenna arrays with beamforming result in major increases in fronthaul capacity required for 5G networks. As a result, a radical re-design of the radio access network is required since traditional fronthaul technologies are not scaleable. In this article the use of analog radio-over-fiber (ARoF) is proposed and demonstrated as a viable alternative which, combined with space division multiplexing in the optical distribution network as well as photonic integration of the required transceivers, shows a path to a scaleable fronthaul solution for 5G. The trade-off between digitized and analog fronthaul is discussed and the ARoF architecture proposed by blueSPACE is introduced. Two options for the generation of ARoF two-tone signals for mm-wave generation via optical heterodyning are discussed in detail, including designs for the implementation in photonic integrated circuits as well as measurements of their phase noise performance. The proposed photonic integrated circuit designs include the use of both InP and SiN platforms for ARoF signal generation and optical beamforming respectively, proposing a joint design that allows for true multi-beam transmission from a single antenna array. Phase noise measurements based on laboratory implementations of ARoF generation based on a Mach–Zehnder modulator with suppressed carrier and with an optical phase-locked loop are presented and the suitability of these transmitters is evaluated though phase noise simulations. Finally, the viability of the proposed ARoF fronthaul architecture for the transport of high-bandwidth mm-wave 5G signals is proven with the successful implementation of a real-time transmission link based on an ARoF baseband unit with full real-time processing of extended 5G new radio signals with 800 MHz bandwidth, achieving transmission over 10 km of 7-core single-mode multi-core fiber and 9 m mm-wave wireless at 25.5 GHz with bit error rates below the limit for a 7% overhead hard decision forward error correction.

A U-Band PLL Using Implicit Distributed Resonators for Sub-THz Wireless Transceivers in 40 nm CMOS

A U-band phase-locked loop (PLL) with implicit distributed resonators in the voltage-controlled oscillator (VCO) and injection-locked frequency divider (ILFD) using 40 nm CMOS is investigated in this brief. While LC -based, transformer-based, and distributed resonators are typically adopted for mm-wave and sub-terahertz applications, implicit distributed resonators are proposed to enhance the oscillation frequency of the VCO and expand the locking range of the ILFD. The operating principles and the characteristics of the proposed implicit distributed resonators are discussed for intuitive insight. The presented PLL occupies 0.53 mm2 core area and has 81.8 mW power consumption. The PLL achieves a measured frequency range of 8.15 GHz (16%) from 46.75 GHz to 54.9 GHz. The measured phase noise is −91.8 dBc/Hz at 1 MHz offset frequency from a carrier of 46.75 GHz. The proposed U-band PLL can provide a clear and stable local oscillation signal for the transceivers operating at mm-wave and sub-terahertz (sub-THz) frequency band.

주파수 잠금회로(FLL)를 이용한 주파수 합성기

Unlike conventional frequency-locked loop(FLL) oscillators, in this paper, a novel FLL-frequency synthesizer(FLL-FS) is proposed using a resonator with a resonance frequency fL lower than the oscillation frequency. The proposed FLL-FS oscillates at nfL(n is an integer), and comprises a voltage-controlled oscillator(VCO), frequency divider, and frequency detector(FD). To verify the feasibility of the proposed FLL-FS structure, a prototype FLL-FS is presented. The selected resonator was a surface-mount ceramic resonator with a resonance frequency of 11.255 MHz. The FD consists of the selected resonator and an XOR-phase detector. The frequency divider is a fixed-frequency divider and has a division ratio of 128/129. The selected VCO has a frequency tuning range that includes a multiplied frequency of 11.255 MHz by 128/129. The fabricated frequency synthesizer demonstrated a successful FLL-FS operation, and the measured phase noise was −91 dBc/Hz at an offset frequency of 100 kHz.

Self-Forced Opto-Electronic Oscillators Using Sagnac-Loop PM-IM Convertor

Efficient phase to intensity conversion is key in Sagnac-loop based opto-electronic oscillators ( OEO). This paper features analytical modeling of phase to intensity conversion in practical Sagnac-loop interferometers, with practical coupling imbalance in 3-dB optical coupler, polarization imbalance of the non-reciprocal optical phase shifter (NRPS), and cross-talk ratio in polarization maintaining fiber (PMF). Single-sideband (SSB) phase noise of self-forced frequency stabilization technique of this OEO is also modelled using self-injection locked (SIL) and dual self-phase locked loop (DSPLL); the free-running and forced modeling results of Sagnac-loop based OEO matches with experimentally measured phase noise results. The measured phase noise of the SILDPLL based OEO at 10 GHz is −131 dBc/Hz at offset frequency of 10 kHz with approximately 11 dB phase noise reduction compared to the results of free-running OEO. Self-forced stabilization of OEO results in timing jitter of 19.5 fs, a factor of 6 times reduction in the free-running performance.

Pulse Timing Jitter Estimated From Optical Phase Noise in Mode-Locked Semiconductor Quantum Dash Lasers

The determination of timing jitter obtained from optical phase noise measurements is investigated in InAs/InP quantum dash Fabry–Perot mode-locked coherent comb lasers with different pulse repetition rates. The results are compared with those determined through a direct measurement of the first harmonic of the RF power spectrum. Very good agreement is achieved. The ability to measure the timing jitter from optical phase noise is not restricted by the repetition rate of the laser being studied, allowing it to be applied to extremely high repetition rate lasers. Using these lasers we demonstrate 5.4 Tbit/s (PAM-4 48 × 28 GBaud PDM) and 10.3 Tbit/s (16 QAM 56 × 23 GBaud PDM) aggregate data transmission capacity. The ultra-low timing jitter exhibited by these devices make them excellent sources for multi-terabit optical networks.

Sensitivity and noise analysis of SAW magnetic field sensors with varied magnetostrictive layer thicknesses

In this work surface acoustic Love wave delay line magnetic field sensors with varying magnetostrictive layer thicknesses are discussed. Amorphous FeCoSiB is used as the sensitive layer with a thickness variation in the range of 25–400 nm. Each sensor is analyzed both by magneto-optical methods as well as electrical signal and noise measurements. In accordance with previously reported simulation results, the impact on the acoustically propagating wave's velocity distinctly increased with thicker magnetostrictive layers leading to magnetic sensitivities as high as 35 rad/T for a delay line coated with 400 nm thick FeCoSiB. Measurements of the sensor-intrinsic phase noise revealed distinct flicker phase noise that scales proportionally with the increase in magnetic sensitivity, thus leading to virtually constant limits of detection (LOD). Assuming that the observed flicker noise is caused by magnetic hysteresis losses due to the high-frequency excitation of the magnetic material, the LOD's independence of the magnetic sensitivity can even be shown analytically. However, it also becomes clear that such sensors need a magnetostrictive coating with a minimum thickness of at least 50 nm such that the signal-to-noise ratio is dominated by the magnetic material and not by fundamental noise contributions of the substrate. On the contrary, layers with thickness above 300 nm lead to distinct higher hysteresis losses that outrun the simultaneous increase in sensitivity, thus leading to a worse overall performance.

New 20 GHz push–push common‐collector Colpitts VCO

A wide-band push–push common-collector Colpitts voltage-controlled oscillator (VCO) usingimpedance peaking network and gain enhancing technique is proposed in this work.The impedance peaking network is introduced to increase the coupling factor ofthe differential inductor in the inductorcapacitor (LC) tank without sacrificing the quality factor. The impedancepeaking technique could guarantee the push–push VCO unconditionally oscillatingin a differential mode without degrading the phase noise performance. The gainenhancing technique employs an LC resonator in series with the emitterdegeneration resistor in the common-collector amplifier in the VCO core toimprove the VCO oscillating amplitude and then improve the phase noiseperformance. The proposed VCO oscillates at around 20 GHz with >10.5%frequency tuning range from 18.9 to 21.4 GHz across temperature from −40 to125°C. The measured phase noise is lower than −107 dBc/Hz at 1 MHz offset acrossthe entire working temperature (−40 125°C). The whole VCO dissipates 45 mA under3.3 V power supply, and the typical figure of merit is around −177.92.

Design and Analysis of Collective Pulse Oscillators

Collective pulse oscillators (CPOs) are novel designs constructed using pulse regenerative amplifiers that exhibit time-variant gate delay based on the residual charge from past state. This property makes it possible to achieve precise phase resolutions smaller than a pulse gate delay and/or provide identical phase taps at multiple physical locations. CPOs exhibit temporal phase error correction that results in an improvement in frequency stability ∝ -10 log p for power ∝ p across all timescales beyond the correction settling time. While CPOs result in device noise-based figure of merits (FoMs) comparable to that of ring oscillators, they are more resilient to power-coupled and impulse noise. This article presents a systematic time-domain analysis of the properties of CPOs based on an abstract model that captures the time-variant delay of pulse gates. Closedform analytic solutions for CPOs disturbed by impulse noise are derived, and higher order CPOs with continuous noise injection are analyzed using behavioral simulations and characterized using Allan deviation. Hspice simulation results are presented to validate the model and compare CPOs with ring oscillators. Allan deviation and phase noise measurements on CPOs of 8 and 40 gates fabricated in GFUS8RF (130-nm) technology corroborate the theory and simulation results.

Bayesian filtering framework for noise characterization of frequency combs.

Amplitude and phase noise correlation matrices are of fundamental importance for studying noise properties of frequency combs. They include information about the origin of noise sources as well as the scaling and correlation of the noise across the comb lines. These matrices provide an insight that is essential for obtaining low-noise performance which is important for, e.g., applications in optical communication, low-noise microwave signal generation, and distance measurements. Estimation of amplitude and phase noise correlation matrices requires highly-accurate measurement technique which can distinguishes between noise sources coming from the frequency comb and the measurement system itself. Bayesian filtering provides a theoretically optimum approach for filtering of measurement noise and thereby, the most accurate measurement of phase and amplitude noise. In this paper, a novel Bayesian filtering based framework for joint estimation of amplitude and phase noise of multiple frequency comb lines is proposed, and demonstrated for phase noise characterization. Compared to the conventional approaches, that do not employ any measurement noise filtering, the proposed approach provides significantly more accurate measurements of correlation matrices, operates over a wide range of signal-to-noise-ratios and gives an insight into comb's dynamics at short scales (<10-8 s).

OFDM tolerance to additive white Gaussian and laser phase noises in optical heterodyning systems accompanied by the feasible pilot-assisted equalization

It is well known that the performance of orthogonal frequency division multiplexing (OFDM) is limited by phase noise, which depends on the laser linewidths for coherent-detection radio over fiber (RoF) systems. In this manuscript, we present numerical and theoretical results to analyze the combined effects of phase and additive white Gaussian noises in the performance of RoF-OFDM schemes with the feasible pilot-based channel corrector. This phase-noise compensator is adopted due to its effectiveness as well as simplicity. It is shown that as the subcarrier modulation format increases, the required radio frequency linewidth for overcoming the FEC limit decreases by a factor of 10 times. Also, there is a signal–noise ratio penalty of 7 dB. Furthermore, it is demonstrated that the bit error rate enhances as the product of the laser linewidths and OFDM symbol period decreases because the pilot-assisted equalization method acts as a high-pass filter for phase noise. We finally discovered that the intermediate-frequency (IF) carrier suppression is not mandatory; the system performance is not affected by selecting properly the carrier–signal ratio and IF. To confirm the previous observation, a novel way to measure phase noise in RoF-OFDM signals accompanied by the IF carrier is proposed. The mean integral phase noise comes from the adaptation of the root mean square phase deviation of the single-carrier systems. This work serves as a guideline for the study and design of OFDM-based RoF schemes susceptible to direct and coherent detections.

A sub-harmonic injection locking clock multiplier with FLL PVT calibrator

Using the sub-harmonic injection locking technique, an enhanced differential Digitally Controlled Ring Oscillator (DCRO) with improved phase noise performance is proposed in this paper. All circuit blocks were implemented using digital design flow and designed using a hardware description language. A Frequency Locked Loop-based Process, Voltage and Temperature (PVT) calibrator was utilized to overcome PVT variations. The design was fabricated in 65 nm CMOS technology and its area is 0.017 mm2. The measured phase noise at 1 MHz offset and RMS jitter are −128 dB/Hz and 197fs, respectively. The design was tested in the presence of voltage and temperature variations. The maximum jitter difference percentage is 13.7% at 70 °C and 1.1 V and the phase noise value changes by a maximum of 0.7 dB over the whole range of voltages and temperatures. Furthermore, when the design was tested in the presence of switching noise, it provides up to 7 dB improvement in phase noise when compared to a single ended version of the DCRO.

300-GHz InP HBT Quadrature VCO With Integrated Mixer

A 300-GHz quadrature voltage-controlled oscillator (QVCO) integrated with a pair of mixers based on an InP heterojunction bipolar transistor (HBT) technology has been developed. A super-harmonic coupling technique was applied to generate the quadrature signal in the QVCO. The oscillation frequency tuning range is 24.8 GHz (from 286.1 to 310.9 GHz), and the frequency range maintaining the quadrature operation (within ±10°) is 4.8 GHz (297.2–302.0 GHz). The maximum output power of the QVCO was measured as 0.46 dBm at 286.3 GHz. The measured phase noise is −91.4 dBc/Hz with 10 MHz offset at 294.2 GHz. The integrated QVCO-mixer consumes a dc power of 167.5 mW.

Photonic-assisted single system for microwave frequency and phase noise measurement

We propose a photonic-assisted single system for measuring the frequency and phase noise of microwave signals in a large spectral range. Both the frequency and phase noise to be measured are extracted from the phase difference between the signal under testing and its replica delayed by a span of fiber and a variable optical delay line (VODL). The system calibration, frequency measurement, and phase noise measurement are performed by adjusting the VODL at different working modes. Accurate frequency and phase noise measurement for microwave signals in a large frequency range from 5 to 50 GHz is experimentally demonstrated.

A Programmable Frequency Divider With a Full Modulus Range and 50% Output Duty Cycle

Programmable frequency dividers with wide modulus range and 50% output duty cycle are highly desirable in the design of frequency synthesizers and phase-locked loops. However, most of the conventional dividers cannot simultaneously achieve a 50% output duty cycle and full modulus range. A programmable frequency divider with a full modulus range, 50% output duty cycle and low phase noise is presented in this paper. To achieve a 50% output duty cycle, the divider employs a novel programmable down-counter based on a modified D flip-flop with a load function. The divider, which was fabricated in a standard 0.18-μm CMOS process, achieves a full 1 to 256 modulus range, 50% output duty cycle, and can operate up to 2.3 GHz with a 1.8-V supply voltage and a power consumption of 3.4 mW. The measured phase noise is -141 dBc/Hz at the frequency offset of 1 MHz when the divider is working at a 1-GHz operational frequency and a division ratio of 10.

Optomechanical microwave oscillator and frequency comb generation in a full phononic bandgap 1D optomechanical crystal cavity

In this work we show that a silicon optomechanical crystal cavity can be used as an optomechanical oscillator when driven to the phonon lasing condition with a blue-detuned laser. The optomechanical cavity is designed to have a breathing like mode vibrating at Ωm/2π =3.897 GHz in a full phononic bandgap. Our measurements show that the first harmonic displays a phase noise of -100 dBc/Hz at 100 kHz. Stronger bluedetuned driving leads eventually to the formation of an optomechanical frequency comb, with lines spaced by the mechanical frequency. The measured phase noise grows up with the harmonic number, as in classical harmonic mixing. We present real-time measurements of the comb waveform and show that it can be adjusted to a theoretical model recently presented. Our results suggest that silicon optomechanical cavities can play a role in integrated microwave photonics.

Two wide-tuning-range mm-wave VCOs with SCTL and SCCPW in 45 nm SOI CMOS for 5G applications

A switched coupled transmission line (SCTL) method with high Q and flexible structure is proposed for mm-wave VCO to improve tuning range (TR), meanwhile maintaining low phase noise, low power dissipation and zero additional area. This TR extension method is also proved effective in a switched coupled coplanar waveguide (SCCPW) VCO. Fabricated in 45 nm SOI CMOS, the SCTL-VCO achieves 38.74% TR from 39.46 to 58.42 GHz, increased by 29.2% compared to the reference TL-VCO. The SCCPW-VCO achieves 38.83% TR from 38.69 to 57.33 GHz, increased by 31.9% compared to the reference CPW-VCO. The measured phase noise of SCTL-VCO and SCCPW-VCO over the entire frequency tuning range is from $$-$$ 106 to $$-$$ 116.8 and $$-$$ 106.1 to $$-$$ 116 dBc/Hz at 10 MHz offset, while the corresponding FOM$$_T$$ is from $$-$$ 181.7 to $$-$$ 192.5 and $$-$$ 181.6 to $$-$$ 191.5 dBc/Hz, respectively. Each VCO dissipates 8.6–10.8 mW from 0.7 V power supply.

A 230-GHz High-Power and Wideband Coupled Standing Wave VCO in 65-nm CMOS

This article presents a 230-GHz wideband harmonic voltage-controlled oscillator (VCO) with large output power based on a compact and low-loss structure of coupled standing wave oscillators. In order to boost the output power, oscillators are coupled together without adding extra passive loss to the circuit. Transistors with inductive drain impedances provide the necessary negative resistance to the oscillators while simultaneously acting as active variable capacitors for frequency tuning and generate the desired second-harmonic power through their nonlinearities. Transmission lines at the drains are responsible for creating the inductive impedance as well as coupling adjacent oscillators and routing and combining the output power. Therefore, the circuit has a compact structure that minimizes passive losses. A varactor-less frequency tuning scheme is used and allows for wideband operation without sacrificing the output power. In addition to oscillator coupling and minimizing the losses, the output power has been boosted by engineering the harmonic impedance that is seen by the transistors in the circuit. The prototype chip was implemented in a 65-nm CMOS process. The output power of the VCO covers 219-238 GHz frequency band (8.35% tuning range) and delivers 3.4-dBm maximum output power. The minimum measured phase noise is -105.8 dBc/Hz (at 10-MHz offset) while consuming 195 mW from a 1.5-V supply.