Showing papers on "Phase noise published in 2012"
TL;DR: In this paper, a split-spectrum amplitude-decorrelation angiography (SSADA) was proposed to improve the signal-to-noise ratio (SNR) of flow detection.
Abstract: Amplitude decorrelation measurement is sensitive to transverse flow and immune to phase noise in comparison to Doppler and other phase-based approaches. However, the high axial resolution of OCT makes it very sensitive to the pulsatile bulk motion noise in the axial direction. To overcome this limitation, we developed split-spectrum amplitude-decorrelation angiography (SSADA) to improve the signal-to-noise ratio (SNR) of flow detection. The full OCT spectrum was split into several narrower bands. Inter-B-scan decorrelation was computed using the spectral bands separately and then averaged. The SSADA algorithm was tested on in vivo images of the human macula and optic nerve head. It significantly improved both SNR for flow detection and connectivity of microvascular network when compared to other amplitude-decorrelation algorithms.
1,507 citations
Journal Article•
TL;DR: In this paper, a split-spectrum amplitude-decorrelation angiography (SSADA) was proposed to improve the signal-to-noise ratio (SNR) of flow detection.
Abstract: Amplitude decorrelation measurement is sensitive to transverse flow and immune to phase noise in comparison to Doppler and other phase-based approaches. However, the high axial resolution of OCT makes it very sensitive to the pulsatile bulk motion noise in the axial direction. To overcome this limitation, we developed split-spectrum amplitude-decorrelation angiography (SSADA) to improve the signal-to-noise ratio (SNR) of flow detection. The full OCT spectrum was split into several narrower bands. Inter-B-scan decorrelation was computed using the spectral bands separately and then averaged. The SSADA algorithm was tested on in vivo images of the human macula and optic nerve head. It significantly improved both SNR for flow detection and connectivity of microvascular network when compared to other amplitude-decorrelation algorithms.
1,151 citations
06 May 2012
TL;DR: In this article, mid and near-IR optical frequency combs were generated in ultra high Q crystalline and integrated SiN microcavities, and universal dynamics that influences phase noise was described.
Abstract: Mid and near-IR optical frequency combs generation in ultra high Q crystalline and integrated SiN microcavities is presented Moreover, universal dynamics that influences phase noise is described
574 citations
TL;DR: In this article, a radar system with an ultra-wide FMCW ramp bandwidth of 25.6 GHz around a center frequency of 80 GHz is presented, which is based on a monostatic fully integrated SiGe transceiver chip, and stabilized using conventional fractional-N PLL chips at a reference frequency of 100 MHz.
Abstract: A radar system with an ultra-wide FMCW ramp bandwidth of 25.6 GHz (≈32%) around a center frequency of 80 GHz is presented. The system is based on a monostatic fully integrated SiGe transceiver chip, which is stabilized using conventional fractional-N PLL chips at a reference frequency of 100 MHz. The achieved in-loop phase noise is ≈ -88 dBc/Hz (10 kHz offset frequency) for the center frequency and below ≈-80 dBc/Hz in the wide frequency band of 25.6 GHz for all offset frequencies >;1 kHz. The ultra-wide PLL-stabilization was achieved using a reverse frequency position mixer in the PLL (offset-PLL) resulting in a compensation of the variation of the oscillators tuning sensitivity with the variation of the N-divider in the PLL. The output power of the transceiver chip, as well as of the mm-wave module (containing a waveguide transition), is sufficiently flat versus the output frequency (variation <;3 dB). In radar measurements using the full bandwidth an ultra-high spatial resolution of 7.12 mm was achieved. The standard deviation between repeated measurements of the same target is 0.36 μm.
230 citations
TL;DR: It is shown that a class of resonators having surface-loss-limited Q factors can operate over a wide range of repetition rates with minimal variation in threshold power, and a new, surface- loss-limited resonator illustrates the idea.
Abstract: Microresonator-based frequency combs (microcombs or Kerr combs) can potentially miniaturize the numerous applications of conventional frequency combs. A priority is the realization of broadband (ideally octave spanning) spectra at detectable repetition rates for comb self-referencing. However, access to these rates involves pumping larger mode volumes and hence higher threshold powers. Moreover, threshold power sets both the scale for power per comb tooth and also the optical pump. Along these lines, it is shown that a class of resonators having surface-loss-limited Q factors can operate over a wide range of repetition rates with minimal variation in threshold power. A new, surface-loss-limited resonator illustrates the idea. Comb generation on mode spacings ranging from 2.6 to 220 GHz with overall low threshold power (as low as 1 mW) is demonstrated. A record number of comb lines for a microcomb (around 1900) is also observed with pump power of 200 mW. The ability to engineer a wide range of repetition rates with these devices is also used to investigate a recently observed mechanism in microcombs associated with dispersion of subcomb offset frequencies. We observe high-coherence phase locking in cases where these offset frequencies are small enough so as to be tuned into coincidence. In these cases, a record-low microcomb phase noise is reported at a level comparable to an open-loop, high-performance microwave oscillator.
206 citations
TL;DR: This Letter presents a novel absolute phase recovery technique with phase coding that uses phase instead of intensity to determine codewords, and it could achieve a faster measurement speed, since three additional images can represent more than 8(2(3) unique codeword for phase unwrapping.
Abstract: This Letter presents a novel absolute phase recovery technique with phase coding. Unlike the conventional gray-coding method, the codeword is embedded into the phase and then used to determine the fringe order for absolute phase retrieval. This technique is robust because it uses phase instead of intensity to determine codewords, and it could achieve a faster measurement speed, since three additional images can represent more than 8(23) unique codewords for phase unwrapping. Experimental results will be presented to verify the performance of the proposed technique.
187 citations
TL;DR: This work considers the influence of phase noise in the preparation stage of the protocol and argues that taking this noise into account can improve the secret key rate because this source of noise is not controlled by the eavesdropper.
Abstract: As quantum key distribution becomes a mature technology, it appears clearly that some assumptions made in the security proofs cannot be justified in practical implementations. This might open the door to possible side-channel attacks. We examine several discrepancies between theoretical models and experimental setups in the case of continuous-variable quantum key distribution. We study in particular the impact of an imperfect modulation on the security of Gaussian protocols and show that approximating the theoretical Gaussian modulation with a discrete one is sufficient in practice. We also address the issue of properly calibrating the detection setup and in particular the value of the shot noise. Finally, we consider the influence of phase noise in the preparation stage of the protocol and argue that taking this noise into account can improve the secret key rate because this source of noise is not controlled by the eavesdropper.
179 citations
TL;DR: In this article, an optically tunable optoelectronic oscillator (OEO) with a wide frequency tunable range incorporating a tunable microwave photonic filter implemented based on phase-modulation to intensity modulation conversion using a phase-shifted fiber Bragg grating (PS-FBG) is proposed and experimentally demonstrated.
Abstract: An optically tunable optoelectronic oscillator (OEO) with a wide frequency tunable range incorporating a tunable microwave photonic filter implemented based on phase-modulation to intensity-modulation conversion using a phase-shifted fiber Bragg grating (PS-FBG) is proposed and experimentally demonstrated. The PS-FBG in conjunction with two optical phase modulators in the OEO loop form a high-Q, wideband and frequency-tunable microwave photonic bandpass filter, to achieve simultaneously single-frequency selection and frequency tuning. Since the tuning of the microwave filter is achieved by tuning the wavelength of the incident light wave, the tunability can be easily realized at a high speed. A theoretical analysis is performed, which is verified by an experiment. A microwave signal with a frequency tunable from 3 GHz to 28 GHz is generated. To the best of our knowledge, this is the widest frequency tunable range ever achieved by an OEO. The phase noise performance of the OEO is also investigated.
178 citations
TL;DR: A systematic method for characterizing semiconductor-laser phase noise, using a low-speed offline digital coherent receiver, and can predict the bit-error rate (BER) performance of multi-level modulated optical signals at 10 Gsymbol/s.
Abstract: We develop a systematic method for characterizing semiconductor-laser phase noise, using a low-speed offline digital coherent receiver. The field spectrum, the FM-noise spectrum, and the phase-error variance measured with such a receiver can completely describe phase-noise characteristics of lasers under test. The sampling rate of the digital coherent receiver should be much higher than the phase-fluctuation speed. However, 1 GS/s is large enough for most of the single-mode semiconductor lasers. In addition to such phase-noise characterization, interpolating the taken data at 1.25 GS/s to form a data stream at 10 GS/s, we can predict the bit-error rate (BER) performance of multi-level modulated optical signals at 10 Gsymbol/s. The BER degradation due to the phase noise is well explained by the result of the phase-noise measurements.
176 citations
04 Mar 2012
TL;DR: In this paper, the authors demonstrate 1023 Tb/s transmission over 3×80 km of PSCF by employing 548-Gb/s PDM-64QAM single-carrier frequency division multiplexing (SC-FDM) signals with pilot tone and 112-THz ultra-wideband low-noise amplification in the C- and extended L-bands.
Abstract: We demonstrate 1023 Tb/s transmission over 3×80 km of PSCF by employing 548-Gb/s PDM-64QAM single-carrier frequency-division-multiplexing (SC-FDM) signals with pilot tone and 112-THz ultra-wideband low-noise amplification in the C- and extended L-bands
166 citations
TL;DR: A low-phase-noise wide-tuning-range oscillator suitable for scaled CMOS processes that switches between the two resonant modes of a high-order LC resonator that consists of two identical LC tanks coupled by capacitor and transformer.
Abstract: In this paper we will present a low-phase-noise wide-tuning-range oscillator suitable for scaled CMOS processes. It switches between the two resonant modes of a high-order LC resonator that consists of two identical LC tanks coupled by capacitor and transformer. The mode switching method does not add lossy switches to the resonator and thus doubles frequency tuning range without degrading phase noise performance. Moreover, the coupled resonator leads to 3 dB lower phase noise than a single LC tank, which provides a way of achieving low phase noise in scaled CMOS process. Finally, the novel way of using inductive and capacitive coupling jointly decouples frequency separation and tank impedances of the two resonant modes, and makes it possible to achieve balanced performance. The proposed structure is verified by a prototype in a low power 65 nm CMOS process, which covers all cellular bands with a continuous tuning range of 2.5-5.6 GHz and meets all stringent phase noise specifications of cellular standards. It uses a 0.6 V power supply and achieves excellent phase noise figure-of-merit (FoM) of 192.5 dB at 3.7 GHz and >; 188 dB across the entire tuning range. This demonstrates the possibility of achieving low phase noise and wide tuning range at the same time in scaled CMOS processes.
TL;DR: Simulation results demonstrate that by employing the proposed channel and time-varying phase noise estimators the bit-error rate performance of a MIMO system can be significantly improved.
Abstract: Oscillator phase noise limits the performance of high speed communication systems since it results in time varying channels and rotation of the signal constellation from symbol to symbol. In this paper, joint estimation of channel gains and Wiener phase noise in multi-input multi-output (MIMO) systems is analyzed. The signal model for the estimation problem is outlined in detail and new expressions for the Cramer-Rao lower bounds (CRLBs) for the multi-parameter estimation problem are derived. A data-aided least-squares (LS) estimator for jointly obtaining the channel gains and phase noise parameters is derived. Next, a decision-directed weighted least-squares (WLS) estimator is proposed, where pilots and estimated data symbols are employed to track the time-varying phase noise parameters over a frame. In order to reduce the overhead and delay associated with the estimation process, a new decision-directed extended Kalman filter (EKF) is proposed for tracking the MIMO phase noise throughout a frame. Numerical results show that the proposed LS, WLS, and EKF estimators' performances are close to the CRLB. Finally, simulation results demonstrate that by employing the proposed channel and time-varying phase noise estimators the bit-error rate performance of a MIMO system can be significantly improved.
TL;DR: Synchronizing an 8.06 GHz microwave signal from a voltage-controlled oscillator with an optical pulse train from a 77.5 MHz mode-locked Er-fiber laser using a fiber-based optical-microwave phase detector has a potential to provide both subfemtosecond-level short-term phase noise and long- term phase stability in microwave extraction from mode-lock fiber lasers.
Abstract: We synchronize an 8.06 GHz microwave signal from a voltage-controlled oscillator with an optical pulse train from a 77.5 MHz mode-locked Er-fiber laser using a fiber-based optical-microwave phase detector. The residual phase noise between the optical pulse train and the synchronized microwave signal is -133 dBc/Hz (-154 dBc/Hz) at 1 Hz (5 kHz) offset frequency, which results in 838 as integrated rms timing jitter [1 Hz-1 MHz]. The long-term residual phase drift is 847 as (rms) measured over 2 h, which reaches 4×10(-19) fractional frequency instability at 1800 s averaging time. This method has a potential to provide both subfemtosecond-level short-term phase noise and long-term phase stability in microwave extraction from mode-locked fiber lasers.
TL;DR: The phase profile dependence on cavity length and injection current is experimentally evaluated, demonstrating the possibility of efficiently using the wide spectral bandwidth exhibited by these quantum dash structures for the generation of high peak power sub-picosecond pulses with low radio frequency linewidths.
Abstract: Mode locking features of single section quantum dash based lasers are investigated. Particular interest is given to the static spectral phase profile determining the shape of the mode locked pulses. The phase profile dependence on cavity length and injection current is experimentally evaluated, demonstrating the possibility of efficiently using the wide spectral bandwidth exhibited by these quantum dash structures for the generation of high peak power sub-picosecond pulses with low radio frequency linewidths.
TL;DR: In this paper, a copier-PSA scheme is proposed, which consists of a parametric phase-insensitive copier followed by one or more PSAs, and a record-low 1.1 dB noise figure was measured at >;26 dB gain.
Abstract: Frequency nondegenerate phase-sensitive amplifiers (PSAs) have the potential to realize broadband and noiseless amplification. However, the rigorous requirement of phase- and wavelength-locking of the input waves has significantly hampered their progress. In this paper, we review recent research on this type of optical amplifier. This work is based on a copier-PSA scheme, which consists of a parametric phase-insensitive copier followed by one or more PSAs. Broadband gain and noise performance of a fiber-based nondegenerate PSA has been characterized, both theoretically and experimentally. A record-low 1.1 dB noise figure was measured at >;26 dB gain, and a clear phase dependent gain was observed. Moreover, potential applications including phase noise squeezing and ultralow noise, multichannel and modulation-format-transparent linear amplification with up to 6 dB link noise figure advantage over conventional EDFA-amplified links have been experimentally demonstrated. The prospects and practical challenges of this intriguing amplification technology are also discussed.
TL;DR: This letter proposes two novel algorithms for the identification of quadrature amplitude modulation (QAM) signals that are robust with respect to timing, phase, and frequency offsets, and phase noise.
Abstract: This letter proposes two novel algorithms for the identification of quadrature amplitude modulation (QAM) signals. The cyclostationarity-based features used by these algorithms are robust with respect to timing, phase, and frequency offsets, and phase noise. Based on theoretical analysis and simulations, the identification performance of the proposed algorithms compares favorably with that of alternative approaches.
TL;DR: A new technique for generation of programmable-pitch, wideband frequency combs with low phase noise using cavity-less, multistage mixer driven by two tunable continuous-wave pump seeds is demonstrated.
Abstract: We demonstrate new technique for generation of programmable-pitch, wideband frequency combs with low phase noise. The comb generation was achieved using cavity-less, multistage mixer driven by two tunable continuous-wave pump seeds. The approach relies on phase-correlated continuous-wave pumps in order to cancel spectral linewidth broadening inherent to parametric comb generation. Parametric combs with over 200-nm bandwidth were obtained and characterized with respect to phase noise scaling to demonstrate linewidth preservation over 100 generated tones.
TL;DR: In this article, the first fundamental frequency single-chip transceiver operating at -band was described, which integrates on a single chip two 120 GHz voltage-controlled oscillators (VCOs), a 120 GHz divide-by-64 chain, two in-phase/quadrature (IQ) receivers with phase-calibration circuitry, a variable gain transmit amplifier, an antenna directional coupler, a patch antenna, bias circuitry, transmit power detector, and a temperature sensor.
Abstract: This paper describes the first fundamental frequency single-chip transceiver operating at -band. The low-IF monostatic transceiver integrates on a single chip two 120-GHz voltage-controlled oscillators (VCOs), a 120-GHz divide-by-64 chain, two in-phase/quadrature (IQ) receivers with phase-calibration circuitry, a variable gain transmit amplifier, an antenna directional coupler, a patch antenna, bias circuitry, a transmit power detector, and a temperature sensor. A quartz antenna resonator with 6-dBi gain and simulated 50% efficiency is placed directly above the on-chip patch to transmit and receive the 120-GHz signals. The circuit with the above-integrated-circuit antenna occupies an area of 2.2 mm 2.6 mm, consumes 900 mW from 1.2- and 1.8-V supplies, and was wire-bonded in an open-lid 7 mm 7 mm quad-flat no-leads package. Some transceiver performance parameters were characterized on the packaged chip, mounted on an evaluation board, while others, such as receiver noise figure and VCO phase noise at the 120-GHz output were measured on circuit breakouts. The AMOS-varactor VCOs have a typical phase noise of at 1-MHz offset and a tuning range of 115.2-123.9 GHz. The receiver gain and the transmitter output power are each adjustable over a range of 15 dB with a maximum transmitter output power of 3.6 dBm. The receiver IQ phase difference, measured at the IF outputs of the packaged transceiver, is adjustable from 70° to 110°, while the amplitude imbalance remains less than 1 dB. The receiver breakout gain and double-sideband noise figure are 10.5-13 and 10.5-11.5 dB, respectively, with an input compression point of . Several experiments were conducted through the air over distances of up to 2.1 m with a focusing lens placed above the packaged chip.
TL;DR: A new mechanism of SR that is induced by the noise at multiple scales for enhanced detection of weak signals under heavy background noise is explored via multiscale noise tuning according to the property of 1/f noise.
21 Dec 2012
TL;DR: In this article, the authors investigated the root cause of performance bottlenecks in current full-duplex systems and proposed signal models for wideband and MIMO fullduplex networks.
Abstract: Recent experimental results have shown that full-duplex communication is possible for short-range communications However, extending full-duplex to long-range communication remains a challenge, primarily due to residual self-interference even with a combination of passive suppression and active cancellation methods In this paper, we investigate the root cause of performance bottlenecks in current full-duplex systems We first classify all known full-duplex architectures based on how they compute their cancelling signal and where the cancelling signal is injected to cancel self-interference Based on the classification, we analytically explain several published experimental results The key bottleneck in current systems turns out to be the phase noise in the local oscillators in the transmit and receive chain of the full-duplex node As a key by-product of our analysis, we propose signal models for wideband and MIMO full-duplex systems, capturing all the salient design parameters, and thus allowing future analytical development of advanced coding and signal design for full-duplex systems
TL;DR: In this paper, the phase dependence in InGaAs pin photo-diodes illuminated with ultra-short pulses generated by an Erbium-doped fiber-based femtosecond laser was investigated.
Abstract: When a photo-diode is illuminated by a pulse train from a femtosecond laser, it generates microwaves components at the harmonics of the repetition rate within its bandwidth. The phase of these components (relative to the optical pulse train) is known to be dependent on the optical energy per pulse. We present an experimental study of this dependence in InGaAs pin photo-diodes illuminated with ultra-short pulses generated by an Erbium-doped fiber based femtosecond laser. The energy to phase dependence is measured over a large range of impinging pulse energies near and above saturation for two typical detectors, commonly used in optical frequency metrology with femtosecond laser based optical frequency combs. When scanning the optical pulse energy, the coefficient which relates phase variations to energy variations is found to alternate between positive and negative values, with many (for high harmonics of the repetition rate) vanishing points. By operating the system near one of these vanishing points, the typical amplitude noise level of commercial-core fiber-based femtosecond lasers is sufficiently low to generate state-of-the-art ultra-low phase noise microwave signals, virtually immune to amplitude to phase conversion related noise.
TL;DR: In this article, a phase-noise-compensated optical frequency domain reflectometry (PNC-OFDR) was proposed to overcome this limitation by introducing a novel phasenoise compensation technique, and achieved a very high resolution measurement over the fiber link length.
Abstract: Recent progress on novel long-range coherent optical frequency domain reflectometry is reviewed along with its applications to diagnosing problems with optical fiber cables. The measurement range of a conventional C-OFDR is limited to the coherence length of the laser used as the light source, since the phase noise of the laser degrades the sharpness of the beat spectrum. We have developed phase-noise-compensated optical frequency domain reflectometry (PNC-OFDR) to overcome this limitation by introducing a novel phase-noise compensation technique, and we achieved a very high-resolution measurement over the fiber link length. We describe the principle of PNC-OFDR and recent related developments, and discuss its use in diagnosing issues with fiber networks.
TL;DR: Intracavity loss modulation enables offset-frequency control with bandwidths beyond what is possible by pump power modulation and record-low residual phase noise of 144 mrads was achieved with this new locking scheme.
Abstract: Intracavity loss modulation enables offset-frequency control with bandwidths beyond what is possible by pump power modulation. To demonstrate this new method, we use a subwavelength thick graphene electro-optic modulator to stabilize the offset frequency in a Tm:fiber frequency comb at 1.95 μm wavelength. Record-low residual phase noise of 144 mrads was achieved with this new locking scheme.
TL;DR: In this paper, the authors demonstrate 101.7-Tb/s transmission over 355 km spans of standard singlemode fiber (SSMF) at a net spectral efficiency of 11 b/s/Hz.
Abstract: We experimentally demonstrate 101.7-Tb/s transmission over 355 km spans of standard single-mode fiber (SSMF) at a net spectral efficiency of 11 b/s/Hz. A total of 370 dense wavelength-division multiplexed (DWDM) channels spanning the optical C- and L-bands spaced at 25 GHz were used. Each 25-GHz channel were subdivided into four subbands, with each subband carrying a 73.5-Gb/s orthogonal frequency-division multiplexed (OFDM) signal modulated with polarization-division-multiplexing (PDM) 128-ary quadrature amplitude modulation (QAM) at each modulated subcarrier. This experiment was enabled by digital signal processing (DSP) pre-equalization of transmitter impairments, all Raman amplification, heterodyne coherent detection, and DSP postequalization of the channel and receiver impairments, including pilot-based phase noise compensation.
TL;DR: In this article, two monolithically integrated W-band frequency synthesizers are presented, implemented in a 018 μm SiGe BiCMOS with fT/fmax of 200/180 GHz.
Abstract: Two monolithically integrated W-band frequency synthesizers are presented Implemented in a 018 μm SiGe BiCMOS with fT/fmax of 200/180 GHz, both circuits incorporate the same 303-338 GHz PLL core One synthesizer uses an injection-locked frequency tripler (ILFT) with locking range of 928-981 GHz and the other employs a harmonic-based frequency tripler (HBFT) with 3-dB bandwidth of 105 GHz from 909-1014 GHz, respectively The measured RMS phase noise for ILFT- and HBFT-based synthesizers are 54° and 55° (100 kHz to 100 MHz integration), while phase noise at 1 MHz offset is -93 and -92 dBc/Hz, respectively, at 96 GHz from a reference frequency of 125 MHz The measured reference spurs are <; -52 dBc for both prototypes The combined power consumption from 18- and 25-V is 140 mW for both chips The frequency synthesizer is suitable for integration in millimeter-wave (mm-wave) phased array and multi-pixel systems such as W-band radar/imaging and 120 GHz wireless communication
TL;DR: The monolithic structure of the device and the inherent low noise characteristics of quantum dash gain material allow the transmission of a 1 Gbps ON-OFF keyed data signal with the two wavelengths in a free-running state at 146-GHz carrier wave frequency.
Abstract: We report the experimental implementation of a wireless transmission system with a 146-GHz carrier frequency which is generated by optical heterodyning the two modes from a monolithically integrated quantum dash dual-DFB source. The monolithic structure of the device and the inherent low noise characteristics of quantum dash gain material allow us to demonstrate the transmission of a 1 Gbps ON-OFF keyed data signal with the two wavelengths in a free-running state at 146-GHz carrier wave frequency. The tuning range of the device fully covers the W-band (75 - 110 GHz) and the F-band (90 - 140 GHz).
01 Nov 2012
TL;DR: In this article, phase noise in the local oscillator limits the amount of active cancellation of the self-interference signal, and modifying the quality of the oscillator can significantly increase the active cancellation in full-duplex systems.
Abstract: Practical designs of wireless full-duplex are made feasible by reducing self-interference via active and passive methods. However, extending the range to long-range communication remains a challenge, primarily due to residual self-interference even after a combination of active cancellation and passive suppression methods is employed. In this paper, we study the factor that limits the amount of active cancellation in current designs of full-duplex. Through an experiment, we show that phase noise in the local oscillator limits the amount of active cancellation of the self-interference signal. Analysing the design proposed by [1, 2] in detail, we show that modifying the quality of the local oscillator can significantly increase the amount of active cancellation in full-duplex systems.
TL;DR: This work demonstrates the highest integration level of any silicon-based systems in the 94 GHz imaging band in a standard 0.18 μm SiGe BiCMOS process.
Abstract: This paper presents a W-band 2 × 2 focal-plane array (FPA) for passive millimeter-wave imaging in a standard 0.18 μm SiGe BiCMOS process (fT/fmax = 200/180 GHz). The FPA incorporates four Dicke-type receivers representing four imaging pixels. Each receiver employs the direct-conversion architecture consisting of an on-chip slot folded dipole antenna, an SPDT switch, a low noise amplifier, a single-balanced mixer, an injection-locked frequency tripler (ILFT), an IF variable gain amplifier, a power detector, an active bandpass filter and a synchronous demodulator. The LO signal is generated by a shared Ka-band PLL and distributed symmetrically to four local ILFTs. The measured LO phase noise is -93 dBc/Hz at 1 MHz offset from the 96 GHz carrier. This imaging receiver (without antenna) achieves a measured average responsivity and noise equivalent power of 285 MV/W and 8.1 fW/Hz1/2, respectively, across the 86-106 GHz bandwidth, which results a calculated NETD of 0.48 K with a 30 ms integration time. The system NETD increases to 3 K with on-chip antenna due to its low efficiency at W-band. MMW images have been generated in transmission mode. This work demonstrates the highest integration level of any silicon-based systems in the 94 GHz imaging band.
TL;DR: By fabricating high-Q silicon-nitride spiral resonators, frequency combs spanning over 200 nm with free spectral ranges (FSRs) of 80, 40, and 20 GHz are demonstrated using cascaded four-wave mixing.
Abstract: By fabricating high-Q silicon-nitride spiral resonators, we demonstrate frequency combs spanning over 200 nm with free spectral ranges (FSRs) of 80, 40, and 20 GHz using cascaded four-wave mixing. We characterize the RF beat note for the 20 GHz FSR comb, and the measured linewidth of 3.6 MHz is consistent with thermal fluctuations in the resonator due to amplitude noise of the pump source. These combs represent an important advance towards developing a complementary metal-oxide-semiconductor (CMOS)-based system capable of linking the optical and electronic regimes.
TL;DR: The novel phase coding method can be used for absolute phase retrieval with high frequency and six additional fringe images can generate more than 64(2(6) unique codewords for correctabsolute phase retrieval.
Abstract: A recently proposed phase coding method for absolute phase retrieval performs well because its codeword is embedded into phase domain rather than intensity. Then, the codeword can determine the fringe order for the phase unwrapping. However, for absolute phase retrieval with a large number of codewords, the traditional phase coding method becomes not so reliable. In this paper, we present a novel phase coding method to tackle this problem. Six additional fringe images can generate more than 64(2(6)) unique codewords for correct absolute phase retrieval. The novel phase coding method can be used for absolute phase retrieval with high frequency. Experiment results demonstrate the proposed method is effective.