Measurement of phase noise through beat frequency

A design of a 5.6 GHz frequency synthesizer with switched bias LIT VCO and low noise on‐chip LDO regulator for 5G applications

The general principles of designing wide angle, large aperture optical systems are addressed. In particular, the advantages and disadvantages of reflective and refractive optical systems are discussed. It is shown that reflective optics have an inherently smaller field of view than do refractive systems. Conservation of etendue is discussed and directly applied to the determination of focal plane size of all optical systems as well as the central obscuration of systems with reflective primaries.

With the rapid developing of science and technology, large aperture optical system plays an important role in the hightech fields including space optics, astronomical optics, inertial confinement fusion, the detecting and recognizing of space target. However, the problems of the wavefront sensing about large aperture optical system has been totally solved because of the equipment expenses and long manufacturing periods. In order to test the large aperture elements in optical system with cheaper costs and higher resolution, more and more attentions are paid into the wavefront sensing of large aperture optical systems. The scanning pentaprism system is introduced to divide the wavefront of the interferometer into a series of sub-wavefront, and the relative positions of the spot centroid accroding to every sub-wavefront are recorded on the CCD camera. The normal directions of every sub-wavefront are obtained to reconstruct the tested wavefront. Experimental results are accord with the interferometer measure results. The feasibility of the pentaprism scanning method has been validated. Finally the influences of measurement apparatus and environment on the measuring precision is discussed. Which is useful to expand the measuring range to keep high spatial resolution and reduce cost.

Radio frequency (RF) receivers are common in many modern communications and radar systems, and they suffer from many performance degradation factors due to hardware limitations. Among all performance degradation contributors, phase noise and time jitter are particularly troublesome since they cause random errors which are difficult to compensate. The local oscillator in the receiver front end is a major contributor of phase noise, while the analog-to-digital converter (ADC) introduces time jitter. It is desired to know the accumulated effect of individual phase noise sources and time jitter. The total effect of all phase noise and jitter can be represented by an accumulated phase noise term at the ADC's output, called total phase noise (TPN) in this brief. The focus of this work is on measuring and modeling TPN in the RF receiver by applying optimization techniques. In contrast to traditional phase noise measurement that typically requires a high-quality tunable downconverter, a digital approach using the data captured directly by the RF receiver is proposed. In addition, iterative optimization-based TPN spectral model fitting and statistic modeling are introduced. The model is examined using the measured TPN. It is confirmed that the RF receiver TPN can be viewed as a wide-sense stationary zero-mean Gaussian process with certain spectral profile.

An overview of several calibration stages has been studied and developed to obtain an optimum setting for phase and amplitude noise measurements through heterodyne techniques, which allows to measure white and flicker noise from amplifiers in the presence of a carrier signal. A technique to obtain a reliable calibration of phase and gain conversion of the measuring blocks is also presented, where the calibration of conversion factors and null conditions, using amplitude and phase modulators for each, phase and amplitude noise levels, have been fully characterized to suppress uncertainties in the measuring process. Furthermore, we introduce a procedure to measure noise of amplifiers in the presence of carrier signal based on a reference noise source and a known lossy line, which allows to determine the noise delivered from the source generator, and the contribution of the setup required for the measurement. We have found a good correlation of the measurements in small signal in comparison with the Y-factor. White noise of matched passive components was measured with the technique presented, obtaining an error of ±0.15 dB. Measurements of an SiGe-HBT amplifier designed for low phase noise are also reported. The technique has also been applied for flicker noise measurements.

The presence of laser phase noise (or frequency jitter) limits the resolution of a variety of interferometric sensors ranging from fiber optic acoustic sensors to gravitational wave detectors. At low frequencies, 0 to 100 kHz, the laser phase noise in semiconductor and diode pumped solid-state lasers is dominated by 1/f noise, the source of which is not well understood. We report on phase noise measurements for external cavity semiconductor lasers (ECSLs) utilizing a fiber Bragg grating in a compact butterfly package design produced by K2 Optronics. The results show that the phase noise is dominated by 1/f noise for low frequencies (10 to 100 kHz) transitioning to a white noise due to spontaneous emission for f > 100 kHz. We observed a factor of 40 improvement in the magnitude of the 1/f phase noise as compared to previously published results for a Hitachi HLP 1400 830 nm diode laser. The magnitude of the low frequency phase noise ranges from 100 to 10 microradians per meter per root Hz for frequencies ranging from 10 Hz to 2 kHz. These results are within a factor of 10 for phase noise measurements of the more expensive Lightwave Electronics Nd:YAG laser and a variety of Er-doped fiber lasers in this frequency range. For nominally similar ECSLs, experimental results indicate that the phase noise increases for lasers with larger leakage currents. Linewidth measurement results showed a Schawlow-Townes inverse power dependence for output powers up to 33 mWatts with the observed onset of a linewidth floor of 30 kHz. The RIN of the ECSLs varied from -120 to -155 dB Vrms per root Hz for frequencies ranging from 10 to 500 kHz. These RIN results are roughly equal to those observed for the Nd:YAG laser for frequencies less that 100 kHz. In summary, such low phase noise and RIN results make such ECSLs suitable for all but the most sensitive fiber optic sensing applications where the frequency range of interest is below 1 MHz.

Accurate oscillator phase-noise simulation is a key problem in MMIC design, which is not solved satisfactory so far and needs further investigation. In this paper, a Ka-band MMIC oscillator with GaInP/GaAs HBT and on-chip resonator is treated as an example. Measured phase noise reaches ?90 dBc/Hz and below at 100 kHz offset. To evaluate phase-noise prediction, the circuit is simulated using different commercial simulation tools and HBT models. Considerable differences in simulation results are observed.

In this article, we describe the simultaneous digital measurement of both phase (PM) and amplitude (AM) noise of VHF and microwave sources by the direct digitization of the signal-under-test. Our measurement approach takes advantage of a commercially-available, high-dynamic-range analog-to-digital converter driven by a high-performance clock to digitize the signal-under-test with high fidelity. Following digitization, phase and amplitude fluctuations are extracted and converted to PM and AM noise spectra. Measurement of microwave signals is accomplished by the inclusion of a specially-designed low-noise down-converter to translate the signal frequency to the VHF regime while introducing minimal additional signal noise. Measurements made on this system are shown to be in good agreement with those obtained using a conventional heterodyne mixer system. In addition to speeding the characterization of RF sources by simultaneously measuring both PM and AM signal characteristics, the digital noise measurement approach allows the direct measurement of the PM- and AM-noise spectra of more complex signals, such as pulsed CW waveforms, in both the VHF and microwave regimes.

It is realized that full digital phase noise measurement system which computes phase noise spectrum after sampling oscillator's signal using analog to digital converter directly. However, in these reports oscillator pairs are used; i.e. DUT oscillator and reference oscillator pairs are needed. These method needs low phase noise characteristics less than DUT oscillator for reference oscillator, or an oscillator of the same specification is required. On the other hand, in traditional (analog and digital mixed) phase noise measurement, it can measure the DUT's phase noise by using two reference oscillators with calculation of cross-correlation, even if the phase noise of the reference oscillator is greater than the DUT. However, there is no report that two reference oscillators are used in full digital phase noise measurement. In this paper we discuss about full digital phase noise measurement system using two reference oscillator. As a result, it was able to measure the DUT phase noise using two reference oscillators which phase noise were greater than DUT.

VIPR (Vapor Inside-cloud Profiling Radar) is a differential absorption radar operating over 155-175 GHz, covering a portion of the lower frequency flank of the 183 GHz water vapor absorption resonance. Transmitting at a ~1.9 mm wavelength, VIPR is highly sensitive to scattering from small particles comprising clouds and precipitation. Variation of VIPR’s cloud and precipitation echo power with frequency is often dominated by water vapor absorption, allowing humidity profiles to be retrieved along the radar’s beam path. One confounding effect in practical measurements is phase noise carried by the radar’s transmit signal, which can result in strong range sidelobes extending from bright targets and obscuring the echo signals of more weakly scattering clouds. Here we show that the magnitude and shape of phase-noise induced clutter from extended, bright cloud signals can be accurately modeled using a combination of empirical measurements of surface-echo phase noise and an analytic model based on the phase-noise sidelobe magnitude from a theoretical point target. This improved understanding of a potential clutter source in millimeter-wave imagine radar can lead to better performance modeling, and it provides motivation to improve the phase noise of very high frequency local oscillators.

In this paper we present results of amplitude and phase noise analysis and measurements of periodic orbits and relate them to signal-to-noise ratios of subcarrier communication systems. The nonlinear system that we have chosen to investigate is the two-section Fabry-Perot laser diode, which supports self-sustained pulsation dynamics. Theoretical analysis is based on the rate equations with Langevin noise forces with self-consistent auto- and cross-correlation functions. The dynamics with noise is obtained by numerical integration using the fourth-order Runge-Kutta method. The phase and amplitude noise is then obtained using digital filtering and spectral analysis. The noise characteristics are also derived analytically using a perturbation method. Experimentally, the noise characteristics of the periodic orbit are analyzed in the electrical domain after photodetection. With proper bandpass filtering, the amplitude and phase noise of each harmonic in the periodic orbit is characterized independently.

In conventional phase noise metrology, the phase noise of an oscillator is measured by instruments equipped with specialized and sophisticated devices. Such hardware-based testing usually requires high-performance and costly apparatuses. In this paper, we carried out a novel phase noise measurement method based on a mathematical model. The relationship between the phase noise of a radio frequency oscillator and its power spectral density (PSD) was established, different components of the power law phase noise were analyzed in the frequency domain with their characteristic parameters. Based on the complete physical model of an oscillator, we fitted and extracted the parameters for the near-carrier Gaussian and the power law PSD with Levenberg-Marquardt optimization algorithm. The fitted parameters were used to restore the power law phase noise with considerable precision. Experimental validation showed an excellent agreement between the estimation from the proposed method and the data measured by a high-performance commercial instrument. This methodology can be potentially used to realize fast and simple phase noise measurement and reduce the overall cost of hardware.

We propose an ultra-low phase noise oscillator topology that works on the premise that coupling a second identical oscillator core would reduce the overall phase noise by 3 dB. For each core, a high-swing class-C oscillator is used to achieve the lowest phase noise. The realized oscillator is tunable from 4.07-4.91 GHz, drawing 39-59 mA from a 2.15 V power supply. The measured phase noise is -146.7 dBc/Hz and -163.1 dBc/Hz at 3 MHz and 20 MHz offset, respectively, from 4.07 GHz carrier. This is the lowest ever reported phase noise in bulk CMOS IC. This phase noise meets GSM900 normal basestation receiver and mobile station transmitter standards, which have the toughest phase noise requirements in cellular communications.

This paper investigates the applicability of common methods of phase noise measurement and short-term frequency stability measurement to K-band frequencies. A phase-noise testset was designed and implemented to test a unit with a nominal frequency of 17.86 GHz, a nominal integrated phase noise of 3/spl deg/ rms, and a nominal carrier-to-equivalent-noise-spectral-density of 110 dB-Hz. The object was to build the least expensive manual testset within a three month (or less) period. The testset was implemented using mostly commercial off-the-shelf (COTS) instruments. The oscilloscope method was only applicable to measuring instantaneous quantities of phase jitter. The frequency counter method could only be used in an automatic (computer controlled) testset. Although a stand-alone COTS phase noise measurement system was found to be the measurement technique, the system offered much more capability and automation than was needed and was also fairly expensive. A second phase detector method using a superheterodyne receiver, local oscillator signal source, and root mean square voltmeter did not produce the best results; however, the results were attributable to design flaws. The method was still found to be feasible. The SSB phase noise method using a COTS spectrum analyzer was found to be very applicable to K-band testing.

In this paper, a 24GHz frequency source for low phase noise is presented in a 0.18µm CMOS process. The 24GHz frequency source chip is composed of a 12GHz voltage controlled oscillator (VCO) and a 24GHz balanced frequency doubler with class B gate bias. Compared to a conventional complementary VCO, the proposed 12GHz VCO has phase noise improvement by using resistor current sources and substituting the nMOS cross-coupled pair in the conventional complementary VCO for a gm-boosted nMOS differential Colpitts pair. The measured phase noise and fundamental frequency suppression are -107.17dBc/Hz at a 1MHz offset frequency and -20.95dB at 23.19GHz frequency, respectively. The measured frequency tuning range is from 23.19GHz to 24.76GHz drawing 2.72mA at a supply voltage of 1.8V not including an output buffer.