In order to study the effect of weak noise on the sound signal extraction of mouse (Mus musculus Km) inferior collicular (IC) neurons from environments,we examined the changes in frequency tuning curves (FTCs) of 32 n...In order to study the effect of weak noise on the sound signal extraction of mouse (Mus musculus Km) inferior collicular (IC) neurons from environments,we examined the changes in frequency tuning curves (FTCs) of 32 neurons induced by a weak noise relative to 5 dB below minimum threshold of tone (reMT-5 dB) under free field stimulation conditions.The results were as follows:① There were three types of variations in FTCs,sharpened (34.4%),broadened (18.8%),and unaffected (46.9%),nevertheless,only the alteration of sharpened FTCs was statistically different.② Sharpness of frequency tuning induced by a reMT-5 dB noise was very strong.Q 10 and Q 30 of FTCs were increased by (34.42±17.04)% (P=0.026,n=11) and (46.34±22.88)% (P=0.009,n=7).③ The changes of inverse-slopes (ISs,kHz/dB) between high (IS high) and low (IS low) limbs of FTCs were dissymmetry.The IS high of FTCs decreased markedly (P=0.046,n=7),however,there was little change (P=0.947,n=7) in IS low.Our data revealed for the first time that the weak noise could sharpen frequency tuning and increase the sensitivity on the high frequency of sound signal in IC neurons of mouse.展开更多
A 3rd-order Butterworth active-RC complex band-pass filter was presented for Zig Bee(IEEE802.15.4) transceiver applications. The filter adopted cascaded complex pole stages to realize the 3 MHz bandwidth with a centre...A 3rd-order Butterworth active-RC complex band-pass filter was presented for Zig Bee(IEEE802.15.4) transceiver applications. The filter adopted cascaded complex pole stages to realize the 3 MHz bandwidth with a centre frequency of 2 MHz which was required by the Zig Bee transceiver applications. An automatic frequency tuning scheme was also designed to accommodate the performance deterioration due to the process, voltage and temperature(PVT) variations. The whole filter is implemented in a 0.18 μm standard process and occupies an area of 1.3 mm×0.6 mm. The current dissipation is 1.2 m A from a 1.8 V single power supply. Measurement results show that the image rejection ratio(IRR) of the filter is 24.1 d B with a pass-band ripple less than 0.3 d B. The adjacent channel rejection is 29.8 d B@7 MHz and alternate channel rejection 47.5 d B@12 MHz, respectively.展开更多
The optical frequency comb has attracted considerable interest due to its diverse applications in optical atomic clocks,ultra-low-noise microwave generation,dual-comb spectroscopy,and optical communications.The merits...The optical frequency comb has attracted considerable interest due to its diverse applications in optical atomic clocks,ultra-low-noise microwave generation,dual-comb spectroscopy,and optical communications.The merits of large frequency spacing,high integration,and low power consumption have shown that microresonator-based Kerr optical frequency combs will become mainstream in the future.Two methods of pump frequency tuning and self-injection locking were used to obtain Kerr combs in the same silicon nitride microresonators with free spectral ranges of 50 GHz and 100 GHz.Singlesoliton combs are realized with both methods.Simplicity,pump power,spectrum bandwidth,conversion efficiency,and linewidth are compared and analyzed.Our results show that the advantages of pump frequency tuning are a wider spectrum and higher soliton power while the advantages of self-injection locking are simplicity,compactness,low cost,significant linewidth narrowing,and high conversion efficiency.展开更多
This article presents a compact magnetic levitation energy harvester(MLEH)with tunable resonant frequency.Unlike many of the reported tunable harvesters with unknown tuning results,the proposed MLEH can be tuned towar...This article presents a compact magnetic levitation energy harvester(MLEH)with tunable resonant frequency.Unlike many of the reported tunable harvesters with unknown tuning results,the proposed MLEH can be tuned toward designated resonant frequency values within its tuning range.The targeted tuning processes is realized by a nonlinear magnet repulsive force exerted on a Halbach magnet array,combined with a calibrated scaling system.At a sinusoidal acceleration of±0.15 g,the maximum frequency tuning range of the proposed MLEH is 6.3 Hz(8.1–14.4 Hz),which is 77.8%of its resonant MLEH(8.1 Hz).At a frequency of 9.7 Hz,the output power is 462.1μW and the calculated normalized power density is 496μWcm^(−3)g^(−2).展开更多
A fifth/seventh order dual-mode OTA-C complex filter for global navigation satellite system receivers is implemented in a 0.18μm CMOS process.This filter can be configured as the narrow mode of a 4.4 MHz bandwidth ce...A fifth/seventh order dual-mode OTA-C complex filter for global navigation satellite system receivers is implemented in a 0.18μm CMOS process.This filter can be configured as the narrow mode of a 4.4 MHz bandwidth center at 4.1 MHz or the wide mode of a 22 MHz bandwidth center at 15.42 MHz.A fully differential OTA with source degeneration is used to provide sufficient linearity.Furthermore,a ring CCO based frequency tuning scheme is proposed to reduce frequency variation.The measured results show that in narrow-band mode the image rejection ratio（IMRR）is 35 dB,the filter dissipates 0.8 mA from the 1.8 V power supply,and the out-of-band rejection is 50 dB at 6 MHz offset.In wide-band mode,IMRR is 28 dB and the filter dissipates 3.2 mA.The frequency tuning error is less than±2%.展开更多
This paper presents a CMOS G;-C complex filter for a low-IF receiver of the IEEE802.15.4 standard.A pseudo differential OTA with reconfigurable common mode feedback and common mode feed-forward is proposed as well as ...This paper presents a CMOS G;-C complex filter for a low-IF receiver of the IEEE802.15.4 standard.A pseudo differential OTA with reconfigurable common mode feedback and common mode feed-forward is proposed as well as the frequency tuning method based on a relaxation oscillator.A detailed analysis of non-ideality of the OTA and the frequency tuning method is elaborated.The analysis and measurement results have shown that the center frequency of the complex filter could be tuned accurately.The chip was fabricated in a standard 0.35μm CMOS process,with a single 3.3 V power supply.The filter consumes 2.1 mA current,has a measured in-band group delay ripple of less than 0.16μs and an IRR larger than 28 dB at 2 MHz apart,which could meet the requirements of the IEEE802.15.4 standard.展开更多
A 162.5 MHz four-vane radio frequency quadruple（RFQ） accelerator has been developed at the Institute of Modern Physics（IMP） for Injector II of the China ADS linac. The RFQ will operate in continuous wave mode at 1...A 162.5 MHz four-vane radio frequency quadruple（RFQ） accelerator has been developed at the Institute of Modern Physics（IMP） for Injector II of the China ADS linac. The RFQ will operate in continuous wave mode at 100 k W. For the designed 10 mA beam, the additional RF power dissipation will induce a very large reflection of power. A water-temperature controlling system will be used to reduce the power reflection by tuning the frequency of the RFQ. The tuning capability of the water temperature is studied under different configurations of cooling water.Simulations and experiment are compared in this paper. The experimental results agree well with simulation using ANSYS. This can be used as a reference to tune the RFQ in beam commissioning.展开更多
The threat to information security from electromagnetic pollution has sparked widespread interest in the development of microwave absorption materials(MAMs).Although considerable progress has been made in high-perform...The threat to information security from electromagnetic pollution has sparked widespread interest in the development of microwave absorption materials(MAMs).Although considerable progress has been made in high-performance MAMs,little attention was paid to their absorption frequency regulation to respond to variable input frequencies and their stability and durability to cope with complex environments.Here,a highly compressible polyimide-packaging carbon nanocoils/carbon foam(PI@CNCs/CF)fabricated by a facile vacuum impregnation method is reported to be used as a dynamically frequency-tunable and environmentally stable microwave absorber.PI@CNCs/CF exhibits good structural stability and mechanical properties,which allows precise absorption frequency tuning by simply changing its compression ratio.For the first time,the tunable effective absorption bandwidth can cover the whole test frequency band(2−18 GHz)with the broadest effective absorption bandwidth of 10.8 GHz and the minimum reflection loss of−60.5 dB.Moreover,PI@CNCs/CF possesses excellent heat insulation,infrared stealth,self-cleaning,flame retardant,and acid-alkali corrosion resistance,which endows it high reliability even under various harsh environments and repeated compression testing.The frequency-tunable mechanism is elucidated by combining experiment and simulation results,possibly guiding in designing dynamically frequency-tunable MAMs with good environmental stability in the future.展开更多
Background:The masseter vestibular evoked myogenic potential(mVEMP) is a novel test that has been explored in various brainstem lesions. However, it has not yet been studied in individuals with definite Meniere's ...Background:The masseter vestibular evoked myogenic potential(mVEMP) is a novel test that has been explored in various brainstem lesions. However, it has not yet been studied in individuals with definite Meniere's disease. Therefore, the current study aimed to investigate m VEMP responses in individuals with definite Meniere's disease and compare them with those of a reference group.Method:The present study investigated narrowband Claus Elberling chirp-evoked m VEMP responses in 22 ears diagnosed with definite Meniere's disease and 22 ears with hearing sensitivity ≤ 15 dB HL across three stimulation frequencies.Results:m VEMP responses in participants with definite Meniere's disease varied from normal to reduced or absent across three octave frequencies. These individuals exhibited significantly reduced P11-N21 peak-to-peak amplitudes compared to those in the reference group. Although a frequency tuning shift toward 1000 Hz was observed, the inter-frequency amplitude ratio of m VEMP was not found to be a sensitive parameter for detecting individuals with definite Meniere's disease. Additionally, no association was found between the degree of hearing loss or the duration of the disease and m VEMP responses. Conclusion: Participants with definite Meniere's disease exhibited reduced P11-N21 amplitude and a tuning shift toward 1000 Hz. These findings suggest the involvement of the vestibulo-trigeminal reflex pathway in this condition.展开更多
Dynamics of the axial mode transition process in a 0.33-THz second-harmonic gyrotron is investigated to reveal the physical mechanism of realizing broadband frequency tuning in an open cavity circuit. A new interactio...Dynamics of the axial mode transition process in a 0.33-THz second-harmonic gyrotron is investigated to reveal the physical mechanism of realizing broadband frequency tuning in an open cavity circuit. A new interaction mechanism about propagating waves, featured by wave competition and wave cooperation, is presented and provides a new insight into the beam-wave interaction. The two different features revealed in the two different operation regions of low-order axial modes （LOAMs） and high-order axial modes （HOAMs） respectively determine the characteristic of the overall performance of the device essentially. The device performance is obtained by the simulation based on the time-domain nonlinear theory and shows that using a 12-kV/150-mA electron beam and TE 3,4 mode, the second harmonic gyrotron can generate terahertz radiations with frequency-tuning ranges of about 0.85 GHz and 0.60 GHz via magnetic field and beam voltage tuning, respectively. Additionally, some non-stationary phenomena in the mode startup process are also analyzed. The investiga- tion in this paper presents guidance for future developing high-performance frequency-tunable gyrotrons toward terahertz applications.展开更多
Under free field conditions, we used single unit extracellular recording to study the detection of acoustic signals by neurons in the ventral nucleus of the lateral lemniscus(VNLL) in Kunming mouse(Mus musculus). The ...Under free field conditions, we used single unit extracellular recording to study the detection of acoustic signals by neurons in the ventral nucleus of the lateral lemniscus(VNLL) in Kunming mouse(Mus musculus). The results indicate two types of firing patterns in VNLL neurons: onset and sustained. The first spike latency(FSL) of onset neurons was shorter than that of sustained neurons. With increasing sound intensity, the FSL of onset neurons remained stable and that of sustained neurons was shortened, indicating that onset neurons are characterized by precise timing. By comparing the values of Q10 and Q30 of the frequency tuning curve, no differences between onset and sustained neurons were found, suggesting that firing pattern and frequency tuning are not correlated. Among the three types of rate-intensity function(RIF) found in VNLL neurons, the proportion of monotonic RIF is the largest, followed by saturated RIF, and non-monotonic RIF. The dynamic range(DR) in onset neurons was shorter than in sustained neurons, indicating different capabilities in intensity tuning of different firing patterns and that these differences are correlated with the type of RIF. Our results also show that the best frequency of VNLL neurons was negatively correlated with depth, supporting the view point that the VNLL has frequency topologic organization.展开更多
Frequency tunability has become a subject of concern in the field of high-power microwave（HPM） source research.However, little information about the corresponding mode converter is available. A tunable circularly-po...Frequency tunability has become a subject of concern in the field of high-power microwave（HPM） source research.However, little information about the corresponding mode converter is available. A tunable circularly-polarized turnstilejunction mode converter（TCTMC） for high-power microwave applications is presented in this paper. The input coaxial TEM mode is transformed into TE（10） mode with different phase delays in four rectangular waveguides and then converted into a circularly-polarized TE（11） circular waveguide mode. Besides, the rods are added to reduce or even eliminate the reflection. The innovations in this study are as follows. The tunning mechanism is added to the mode converter, which can change the effective length of rectangular waveguide and the distance between the rods installed upstream and the closest edge of the rectangular waveguide, thus improving the conversion efficiency and bandwidth. The conversion efficiency of TCTMC can reach above 98% over the frequency range of 1.42 GHz–2.29 GHz, and the frequency tunning bandwidth is about 47%. Significantly, TCTMC can obtain continuous high conversion efficiency of different frequency points with the change of tuning mechanism.展开更多
In this paper, a novel Voltage-Controlled Oscillator （VCO） using the harmonic control circuit based on the quad-band Composite Right/Left-Handed （CRLH） Transmission Line （TL） is presented to reduce the phase noi...In this paper, a novel Voltage-Controlled Oscillator （VCO） using the harmonic control circuit based on the quad-band Composite Right/Left-Handed （CRLH） Transmission Line （TL） is presented to reduce the phase noise without the reduction of the frequeacy tuning range and miniaturizing the circuit size. The phase noise has been reduced by the quad-band harmonic control circuit which has the short impedance for the second- and third- and fourth- and fifth-hannonic components. The CRLH TL with two Left-Handed （LH） （backward） and two Right-Handed （RH） （forward） pass bands are used to design the quad-band harmonic control circuit. The high- Q resonator has been used to reduce the phase noise, but it has the problem of the frequency timing range reduction. However, the frequency tuning range of the proposed VCO has not reduced because the phase noise has reduced without the high-Q resonator. The miniaturization of the circuit size is achieved by using the quad-band CRLH TL instead of the conventional RH TL, The phase noise of VCO is - 124.43～ - 122.67 dBc/Hz at 100 kHz in the tuning range of 5. 729 ～5.934 GHz.展开更多
Integration of graphene in silicon-based micro-/nanoelectromechanical systems(MEMS/NEMS)marries the robustness of silicon-based materials with the exceptional physical properties of graphene,drastically enhancing the ...Integration of graphene in silicon-based micro-/nanoelectromechanical systems(MEMS/NEMS)marries the robustness of silicon-based materials with the exceptional physical properties of graphene,drastically enhancing the system’s regulation performance which now is key for many advanced applications in nanotechnology.Here,we experimentally demonstrate and theoretically analyze a powerful on-chip integration principle consisting of a hybrid graphene/silicon nitride membrane with metallic leads on top that enables an extremely large static and dynamic parameter regulation.When a static voltage is applied to the leads of the integrated structure,a spatially confined localized electrothermomechanical(ETM)effect results in ultra-wide frequency tuning,deformation(buckling transition)and regulation of the mechanical properties.Moreover,by injecting an alternating voltage to the leads,we can excite the resonator vibrating even far beyond its linear regime without a complex and space consuming actuation system.Our results prove that the scheme provides a compact integrated system possessing mechanical robustness,high controllability,and fast response.It not only expands the limit of the application range of MEMS/NEMS devices,but also enables the further miniaturization of the device.展开更多
This paper presents the design and implementation of a low power wide tuning range baseband filter with an accurate on-chip tuning circuit for reconfigurable multistandard wireless transceivers. The realized low pass ...This paper presents the design and implementation of a low power wide tuning range baseband filter with an accurate on-chip tuning circuit for reconfigurable multistandard wireless transceivers. The realized low pass filter （LPF） is a six-order Butterworth type by cascading three stage active-Gm-RC biquadratic cells. A mod- ified linearization technique is used to improve the filter linearity performance at low power consumption. A new process-independent transconductor matching circuit and a new frequency tuning circuit with frequency compen- sation are proposed to achieve a high precision filter frequency response. The proposed LPF is realized in a 130 nm standard CMOS technology. The measured results show that the LPF exhibits a high bandwidth programmability from 0.1 to 25 MHz with a tuning frequency error less than 2.68% over the wide tuning range. The power consump- tion is scalable, ranging from 0.52 to 5.25 mA, from a 1.2 V power supply while achieving a 26.3 dBm in-band IIP3.展开更多
This paper describes a low phase noise, wide tuning range and high tuning linearity CMOS voltage controlled crystal oscillator IC （VCXO-IC） with LVCMOS and LVPECL output. A differential coupled frequency doubling Co...This paper describes a low phase noise, wide tuning range and high tuning linearity CMOS voltage controlled crystal oscillator IC （VCXO-IC） with LVCMOS and LVPECL output. A differential coupled frequency doubling Colpitts oscillator is adopted to obtain low noise 2x frequency output. Wide tuning range and high lin- earity are simultaneously achieved by using MOS varactor arrays. The measurement results show that the designed VCXO-IC achieves -134 dBc/Hz phase noise at 1 kHz offset frequency and 4-135 ppm output frequency tuning range within 3% linearity by using 40 MHz fundamental AT-cut crystal. The VCXO-IC is fabricated in the chartered 0.35/zm standard CMOS process and occupies a total silicon area of 2.4 mm2.展开更多
The design of a digitally-tunable sixth-order reconfigurable OTA-C filter in a 0.18-μm RFCMOS process is proposed.The filter can be configured as a complex band pass filter or two real low pass filters.An improved di...The design of a digitally-tunable sixth-order reconfigurable OTA-C filter in a 0.18-μm RFCMOS process is proposed.The filter can be configured as a complex band pass filter or two real low pass filters.An improved digital automatic frequency tuning scheme based on the voltage controlled oscillator technique is adopted to compensate for process variations.An extended tuning range（above 8：1） is obtained by using widely continuously tunable transconductors based on digital techniques.In the complex band pass mode,the bandwidth can be tuned from 3 to 24 MHz and the center frequency from 3 to 16 MHz.展开更多
A sixth-order Butterworth Gm-C low-pass filter（LPF） with a continuous tuning architecture has been implemented for a wireless LAN（WLAN） transceiver in 0.35μm CMOS technology.An interior node scaling technique has...A sixth-order Butterworth Gm-C low-pass filter（LPF） with a continuous tuning architecture has been implemented for a wireless LAN（WLAN） transceiver in 0.35μm CMOS technology.An interior node scaling technique has been applied directly to the LPF to improve the dynamic range and the structure of the LPF has been optimized to reduce both the die size and the current consumption.Measurement results show that the filter has 77.5 dB dynamic range,16.3 ns group delay variation,better than 3%cutoff frequency accuracy,and 0 dBm passband IIP3.The whole LPF with the tuning circuit dissipates only 1.42 mA（5 MHz cutoff frequency） or 2.81 mA（10 MHz cutoff frequency） from 2.85 V supply voltage,and only occupies 0.175 mm^2 die size.展开更多
This paper presents a continuously and widely tunable analog baseband chain with a digital-assisted calibration scheme implemented on a 0.13μm CMOS technology.The analog baseband is compliant with several digital bro...This paper presents a continuously and widely tunable analog baseband chain with a digital-assisted calibration scheme implemented on a 0.13μm CMOS technology.The analog baseband is compliant with several digital broadcasting system（DBS） standards,including DVB-S,DVB-S2,and ABS-S.The cut-off frequency of the baseband circuit can be changed continuously from 4.5 to 32 MHz.The gain adjustment range is from 6 to 55.5 dB with 0.5 dB step.The calibration includes automatic frequency tuning（AFT） and automatic DC offset calibration （DCOC） to achieve less than 6%cut-off frequency deviation and 3 mV residual output offset.The out-of-band IIP2 and IIP3 of the overall chain are 45 dBm and 18 dBm respectively,while the input referred noise（IRN） is 17.4 nV/√Hz.All circuit blocks are operated at 2.8 V from LDO and consume current of 20.4 mA in the receiving mode.展开更多
An eighth order active-RC filter for low-IF and zero-IF DVB tuner applications is presented, which is implemented in Butterworth biquad structure. An automatic frequency tuning circuit is introduced to compensate the ...An eighth order active-RC filter for low-IF and zero-IF DVB tuner applications is presented, which is implemented in Butterworth biquad structure. An automatic frequency tuning circuit is introduced to compensate the cut-off frequency variation using a 6-bit switched-capacitor array. Switched-resistor arrays are adopted to cover different cut-off frequencies in low-IF and zero-IF modes. Measurement results show that precise cut-off frequencies at 2.5, 3, 3.5 and 4 MHz in zero-IF mode, 5, 6, 7 and 8 MHz in low-IF mode can be achieved, 60 dB frequency attenuation can be obtained at 20 MHz, and the in-band group delay agrees well with the simulation. Two-tone testing shows the in-band IM3 achieves -52 dB and the out-band IM3 achieves -55 dB with -11 dBm input power. This proposed filter circuit, fabricated in a SMIC 0.18μm CMOS process, consumes 4 mA current with 1.8 V power supply.展开更多
文摘In order to study the effect of weak noise on the sound signal extraction of mouse (Mus musculus Km) inferior collicular (IC) neurons from environments,we examined the changes in frequency tuning curves (FTCs) of 32 neurons induced by a weak noise relative to 5 dB below minimum threshold of tone (reMT-5 dB) under free field stimulation conditions.The results were as follows:① There were three types of variations in FTCs,sharpened (34.4%),broadened (18.8%),and unaffected (46.9%),nevertheless,only the alteration of sharpened FTCs was statistically different.② Sharpness of frequency tuning induced by a reMT-5 dB noise was very strong.Q 10 and Q 30 of FTCs were increased by (34.42±17.04)% (P=0.026,n=11) and (46.34±22.88)% (P=0.009,n=7).③ The changes of inverse-slopes (ISs,kHz/dB) between high (IS high) and low (IS low) limbs of FTCs were dissymmetry.The IS high of FTCs decreased markedly (P=0.046,n=7),however,there was little change (P=0.947,n=7) in IS low.Our data revealed for the first time that the weak noise could sharpen frequency tuning and increase the sensitivity on the high frequency of sound signal in IC neurons of mouse.
基金Projects(61334003,61274026) supported by the National Natural Science Foundation of ChinaProject(K5051225006) supported by the Fundamental Research Fund for the Central Universities,China
文摘A 3rd-order Butterworth active-RC complex band-pass filter was presented for Zig Bee(IEEE802.15.4) transceiver applications. The filter adopted cascaded complex pole stages to realize the 3 MHz bandwidth with a centre frequency of 2 MHz which was required by the Zig Bee transceiver applications. An automatic frequency tuning scheme was also designed to accommodate the performance deterioration due to the process, voltage and temperature(PVT) variations. The whole filter is implemented in a 0.18 μm standard process and occupies an area of 1.3 mm×0.6 mm. The current dissipation is 1.2 m A from a 1.8 V single power supply. Measurement results show that the image rejection ratio(IRR) of the filter is 24.1 d B with a pass-band ripple less than 0.3 d B. The adjacent channel rejection is 29.8 d B@7 MHz and alternate channel rejection 47.5 d B@12 MHz, respectively.
基金supported by the National Key R&D Program of China(No.2020YFB2205804)the National Natural Science Foundation of China(No.62075240)。
文摘The optical frequency comb has attracted considerable interest due to its diverse applications in optical atomic clocks,ultra-low-noise microwave generation,dual-comb spectroscopy,and optical communications.The merits of large frequency spacing,high integration,and low power consumption have shown that microresonator-based Kerr optical frequency combs will become mainstream in the future.Two methods of pump frequency tuning and self-injection locking were used to obtain Kerr combs in the same silicon nitride microresonators with free spectral ranges of 50 GHz and 100 GHz.Singlesoliton combs are realized with both methods.Simplicity,pump power,spectrum bandwidth,conversion efficiency,and linewidth are compared and analyzed.Our results show that the advantages of pump frequency tuning are a wider spectrum and higher soliton power while the advantages of self-injection locking are simplicity,compactness,low cost,significant linewidth narrowing,and high conversion efficiency.
基金supported by the Key Research and Development Program of Shaanxi(Program Nos.2022GXLH-01-20 and 2024GXYBXM-193).
文摘This article presents a compact magnetic levitation energy harvester(MLEH)with tunable resonant frequency.Unlike many of the reported tunable harvesters with unknown tuning results,the proposed MLEH can be tuned toward designated resonant frequency values within its tuning range.The targeted tuning processes is realized by a nonlinear magnet repulsive force exerted on a Halbach magnet array,combined with a calibrated scaling system.At a sinusoidal acceleration of±0.15 g,the maximum frequency tuning range of the proposed MLEH is 6.3 Hz(8.1–14.4 Hz),which is 77.8%of its resonant MLEH(8.1 Hz).At a frequency of 9.7 Hz,the output power is 462.1μW and the calculated normalized power density is 496μWcm^(−3)g^(−2).
基金supported by the National High-Tech Research and Development Program of China(No.2007AA12Z344)
文摘A fifth/seventh order dual-mode OTA-C complex filter for global navigation satellite system receivers is implemented in a 0.18μm CMOS process.This filter can be configured as the narrow mode of a 4.4 MHz bandwidth center at 4.1 MHz or the wide mode of a 22 MHz bandwidth center at 15.42 MHz.A fully differential OTA with source degeneration is used to provide sufficient linearity.Furthermore,a ring CCO based frequency tuning scheme is proposed to reduce frequency variation.The measured results show that in narrow-band mode the image rejection ratio（IMRR）is 35 dB,the filter dissipates 0.8 mA from the 1.8 V power supply,and the out-of-band rejection is 50 dB at 6 MHz offset.In wide-band mode,IMRR is 28 dB and the filter dissipates 3.2 mA.The frequency tuning error is less than±2%.
基金Project supported by the National High Technology Research and Development Program of China(No.2008AA010701)
文摘This paper presents a CMOS G;-C complex filter for a low-IF receiver of the IEEE802.15.4 standard.A pseudo differential OTA with reconfigurable common mode feedback and common mode feed-forward is proposed as well as the frequency tuning method based on a relaxation oscillator.A detailed analysis of non-ideality of the OTA and the frequency tuning method is elaborated.The analysis and measurement results have shown that the center frequency of the complex filter could be tuned accurately.The chip was fabricated in a standard 0.35μm CMOS process,with a single 3.3 V power supply.The filter consumes 2.1 mA current,has a measured in-band group delay ripple of less than 0.16μs and an IRR larger than 28 dB at 2 MHz apart,which could meet the requirements of the IEEE802.15.4 standard.
基金Supported by National Natural Science Foundation of China(91026001)
文摘A 162.5 MHz four-vane radio frequency quadruple（RFQ） accelerator has been developed at the Institute of Modern Physics（IMP） for Injector II of the China ADS linac. The RFQ will operate in continuous wave mode at 100 k W. For the designed 10 mA beam, the additional RF power dissipation will induce a very large reflection of power. A water-temperature controlling system will be used to reduce the power reflection by tuning the frequency of the RFQ. The tuning capability of the water temperature is studied under different configurations of cooling water.Simulations and experiment are compared in this paper. The experimental results agree well with simulation using ANSYS. This can be used as a reference to tune the RFQ in beam commissioning.
基金supported by the National Natural Science Foundation of China(grants 22278101,22068010,and 52365044)the Natural Science Foundation of Hainan Province(grants 120RC454 and 519QN176)the Innovation Project for Scientific and Technological Talents in Hainan Province(grant KJRC2023C08)。
文摘The threat to information security from electromagnetic pollution has sparked widespread interest in the development of microwave absorption materials(MAMs).Although considerable progress has been made in high-performance MAMs,little attention was paid to their absorption frequency regulation to respond to variable input frequencies and their stability and durability to cope with complex environments.Here,a highly compressible polyimide-packaging carbon nanocoils/carbon foam(PI@CNCs/CF)fabricated by a facile vacuum impregnation method is reported to be used as a dynamically frequency-tunable and environmentally stable microwave absorber.PI@CNCs/CF exhibits good structural stability and mechanical properties,which allows precise absorption frequency tuning by simply changing its compression ratio.For the first time,the tunable effective absorption bandwidth can cover the whole test frequency band(2−18 GHz)with the broadest effective absorption bandwidth of 10.8 GHz and the minimum reflection loss of−60.5 dB.Moreover,PI@CNCs/CF possesses excellent heat insulation,infrared stealth,self-cleaning,flame retardant,and acid-alkali corrosion resistance,which endows it high reliability even under various harsh environments and repeated compression testing.The frequency-tunable mechanism is elucidated by combining experiment and simulation results,possibly guiding in designing dynamically frequency-tunable MAMs with good environmental stability in the future.
文摘Background:The masseter vestibular evoked myogenic potential(mVEMP) is a novel test that has been explored in various brainstem lesions. However, it has not yet been studied in individuals with definite Meniere's disease. Therefore, the current study aimed to investigate m VEMP responses in individuals with definite Meniere's disease and compare them with those of a reference group.Method:The present study investigated narrowband Claus Elberling chirp-evoked m VEMP responses in 22 ears diagnosed with definite Meniere's disease and 22 ears with hearing sensitivity ≤ 15 dB HL across three stimulation frequencies.Results:m VEMP responses in participants with definite Meniere's disease varied from normal to reduced or absent across three octave frequencies. These individuals exhibited significantly reduced P11-N21 peak-to-peak amplitudes compared to those in the reference group. Although a frequency tuning shift toward 1000 Hz was observed, the inter-frequency amplitude ratio of m VEMP was not found to be a sensitive parameter for detecting individuals with definite Meniere's disease. Additionally, no association was found between the degree of hearing loss or the duration of the disease and m VEMP responses. Conclusion: Participants with definite Meniere's disease exhibited reduced P11-N21 amplitude and a tuning shift toward 1000 Hz. These findings suggest the involvement of the vestibulo-trigeminal reflex pathway in this condition.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61471007,61531002,61522101,and 11275206)the Seeding Grant for Medicine and Information Science of Peking University,China(Grant No.2014-MI-01)
文摘Dynamics of the axial mode transition process in a 0.33-THz second-harmonic gyrotron is investigated to reveal the physical mechanism of realizing broadband frequency tuning in an open cavity circuit. A new interaction mechanism about propagating waves, featured by wave competition and wave cooperation, is presented and provides a new insight into the beam-wave interaction. The two different features revealed in the two different operation regions of low-order axial modes （LOAMs） and high-order axial modes （HOAMs） respectively determine the characteristic of the overall performance of the device essentially. The device performance is obtained by the simulation based on the time-domain nonlinear theory and shows that using a 12-kV/150-mA electron beam and TE 3,4 mode, the second harmonic gyrotron can generate terahertz radiations with frequency-tuning ranges of about 0.85 GHz and 0.60 GHz via magnetic field and beam voltage tuning, respectively. Additionally, some non-stationary phenomena in the mode startup process are also analyzed. The investiga- tion in this paper presents guidance for future developing high-performance frequency-tunable gyrotrons toward terahertz applications.
基金This study was supported by the National Natural Science Foundation of China （31000493） and the Central China Normal University Independent Scientific Research Project Fund for Youth Scholars （11A01025）
文摘Under free field conditions, we used single unit extracellular recording to study the detection of acoustic signals by neurons in the ventral nucleus of the lateral lemniscus(VNLL) in Kunming mouse(Mus musculus). The results indicate two types of firing patterns in VNLL neurons: onset and sustained. The first spike latency(FSL) of onset neurons was shorter than that of sustained neurons. With increasing sound intensity, the FSL of onset neurons remained stable and that of sustained neurons was shortened, indicating that onset neurons are characterized by precise timing. By comparing the values of Q10 and Q30 of the frequency tuning curve, no differences between onset and sustained neurons were found, suggesting that firing pattern and frequency tuning are not correlated. Among the three types of rate-intensity function(RIF) found in VNLL neurons, the proportion of monotonic RIF is the largest, followed by saturated RIF, and non-monotonic RIF. The dynamic range(DR) in onset neurons was shorter than in sustained neurons, indicating different capabilities in intensity tuning of different firing patterns and that these differences are correlated with the type of RIF. Our results also show that the best frequency of VNLL neurons was negatively correlated with depth, supporting the view point that the VNLL has frequency topologic organization.
基金supported by the National Natural Science Foundation of China(Grant No.61671457)
文摘Frequency tunability has become a subject of concern in the field of high-power microwave（HPM） source research.However, little information about the corresponding mode converter is available. A tunable circularly-polarized turnstilejunction mode converter（TCTMC） for high-power microwave applications is presented in this paper. The input coaxial TEM mode is transformed into TE（10） mode with different phase delays in four rectangular waveguides and then converted into a circularly-polarized TE（11） circular waveguide mode. Besides, the rods are added to reduce or even eliminate the reflection. The innovations in this study are as follows. The tunning mechanism is added to the mode converter, which can change the effective length of rectangular waveguide and the distance between the rods installed upstream and the closest edge of the rectangular waveguide, thus improving the conversion efficiency and bandwidth. The conversion efficiency of TCTMC can reach above 98% over the frequency range of 1.42 GHz–2.29 GHz, and the frequency tunning bandwidth is about 47%. Significantly, TCTMC can obtain continuous high conversion efficiency of different frequency points with the change of tuning mechanism.
文摘In this paper, a novel Voltage-Controlled Oscillator （VCO） using the harmonic control circuit based on the quad-band Composite Right/Left-Handed （CRLH） Transmission Line （TL） is presented to reduce the phase noise without the reduction of the frequeacy tuning range and miniaturizing the circuit size. The phase noise has been reduced by the quad-band harmonic control circuit which has the short impedance for the second- and third- and fourth- and fifth-hannonic components. The CRLH TL with two Left-Handed （LH） （backward） and two Right-Handed （RH） （forward） pass bands are used to design the quad-band harmonic control circuit. The high- Q resonator has been used to reduce the phase noise, but it has the problem of the frequency timing range reduction. However, the frequency tuning range of the proposed VCO has not reduced because the phase noise has reduced without the high-Q resonator. The miniaturization of the circuit size is achieved by using the quad-band CRLH TL instead of the conventional RH TL, The phase noise of VCO is - 124.43～ - 122.67 dBc/Hz at 100 kHz in the tuning range of 5. 729 ～5.934 GHz.
基金financial support from the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)through Project-ID 425217212(SFB 1432)and project 510766045the major program in digital intelligence,Shapingba,Chongqing(Grant No.20240204)the Wisconsin Alumni Research Foundation(WARF)via the Accelerator Program.
文摘Integration of graphene in silicon-based micro-/nanoelectromechanical systems(MEMS/NEMS)marries the robustness of silicon-based materials with the exceptional physical properties of graphene,drastically enhancing the system’s regulation performance which now is key for many advanced applications in nanotechnology.Here,we experimentally demonstrate and theoretically analyze a powerful on-chip integration principle consisting of a hybrid graphene/silicon nitride membrane with metallic leads on top that enables an extremely large static and dynamic parameter regulation.When a static voltage is applied to the leads of the integrated structure,a spatially confined localized electrothermomechanical(ETM)effect results in ultra-wide frequency tuning,deformation(buckling transition)and regulation of the mechanical properties.Moreover,by injecting an alternating voltage to the leads,we can excite the resonator vibrating even far beyond its linear regime without a complex and space consuming actuation system.Our results prove that the scheme provides a compact integrated system possessing mechanical robustness,high controllability,and fast response.It not only expands the limit of the application range of MEMS/NEMS devices,but also enables the further miniaturization of the device.
基金supported by the Scientific Research Plan Projects of Hebei Education Department(No.Q2012019)
文摘This paper presents the design and implementation of a low power wide tuning range baseband filter with an accurate on-chip tuning circuit for reconfigurable multistandard wireless transceivers. The realized low pass filter （LPF） is a six-order Butterworth type by cascading three stage active-Gm-RC biquadratic cells. A mod- ified linearization technique is used to improve the filter linearity performance at low power consumption. A new process-independent transconductor matching circuit and a new frequency tuning circuit with frequency compen- sation are proposed to achieve a high precision filter frequency response. The proposed LPF is realized in a 130 nm standard CMOS technology. The measured results show that the LPF exhibits a high bandwidth programmability from 0.1 to 25 MHz with a tuning frequency error less than 2.68% over the wide tuning range. The power consump- tion is scalable, ranging from 0.52 to 5.25 mA, from a 1.2 V power supply while achieving a 26.3 dBm in-band IIP3.
基金Project supported by the National Natural Science Foundation of China(No.61350007)
文摘This paper describes a low phase noise, wide tuning range and high tuning linearity CMOS voltage controlled crystal oscillator IC （VCXO-IC） with LVCMOS and LVPECL output. A differential coupled frequency doubling Colpitts oscillator is adopted to obtain low noise 2x frequency output. Wide tuning range and high lin- earity are simultaneously achieved by using MOS varactor arrays. The measurement results show that the designed VCXO-IC achieves -134 dBc/Hz phase noise at 1 kHz offset frequency and 4-135 ppm output frequency tuning range within 3% linearity by using 40 MHz fundamental AT-cut crystal. The VCXO-IC is fabricated in the chartered 0.35/zm standard CMOS process and occupies a total silicon area of 2.4 mm2.
基金supported by the National High Technology Research and Development Program of China(No.2007AA12Z344)
文摘The design of a digitally-tunable sixth-order reconfigurable OTA-C filter in a 0.18-μm RFCMOS process is proposed.The filter can be configured as a complex band pass filter or two real low pass filters.An improved digital automatic frequency tuning scheme based on the voltage controlled oscillator technique is adopted to compensate for process variations.An extended tuning range（above 8：1） is obtained by using widely continuously tunable transconductors based on digital techniques.In the complex band pass mode,the bandwidth can be tuned from 3 to 24 MHz and the center frequency from 3 to 16 MHz.
文摘A sixth-order Butterworth Gm-C low-pass filter（LPF） with a continuous tuning architecture has been implemented for a wireless LAN（WLAN） transceiver in 0.35μm CMOS technology.An interior node scaling technique has been applied directly to the LPF to improve the dynamic range and the structure of the LPF has been optimized to reduce both the die size and the current consumption.Measurement results show that the filter has 77.5 dB dynamic range,16.3 ns group delay variation,better than 3%cutoff frequency accuracy,and 0 dBm passband IIP3.The whole LPF with the tuning circuit dissipates only 1.42 mA（5 MHz cutoff frequency） or 2.81 mA（10 MHz cutoff frequency） from 2.85 V supply voltage,and only occupies 0.175 mm^2 die size.
基金supported by the National Natural Science Foundation of China(Nos.61176093,51072171)
文摘This paper presents a continuously and widely tunable analog baseband chain with a digital-assisted calibration scheme implemented on a 0.13μm CMOS technology.The analog baseband is compliant with several digital broadcasting system（DBS） standards,including DVB-S,DVB-S2,and ABS-S.The cut-off frequency of the baseband circuit can be changed continuously from 4.5 to 32 MHz.The gain adjustment range is from 6 to 55.5 dB with 0.5 dB step.The calibration includes automatic frequency tuning（AFT） and automatic DC offset calibration （DCOC） to achieve less than 6%cut-off frequency deviation and 3 mV residual output offset.The out-of-band IIP2 and IIP3 of the overall chain are 45 dBm and 18 dBm respectively,while the input referred noise（IRN） is 17.4 nV/√Hz.All circuit blocks are operated at 2.8 V from LDO and consume current of 20.4 mA in the receiving mode.
基金Project supported by the National High Technology Research and Development Program of China (No.2007AA01Z282)
文摘An eighth order active-RC filter for low-IF and zero-IF DVB tuner applications is presented, which is implemented in Butterworth biquad structure. An automatic frequency tuning circuit is introduced to compensate the cut-off frequency variation using a 6-bit switched-capacitor array. Switched-resistor arrays are adopted to cover different cut-off frequencies in low-IF and zero-IF modes. Measurement results show that precise cut-off frequencies at 2.5, 3, 3.5 and 4 MHz in zero-IF mode, 5, 6, 7 and 8 MHz in low-IF mode can be achieved, 60 dB frequency attenuation can be obtained at 20 MHz, and the in-band group delay agrees well with the simulation. Two-tone testing shows the in-band IM3 achieves -52 dB and the out-band IM3 achieves -55 dB with -11 dBm input power. This proposed filter circuit, fabricated in a SMIC 0.18μm CMOS process, consumes 4 mA current with 1.8 V power supply.
