A 13bit,pipelined analog-to-digital converter （ADC） designed to achieve high linearity is described. The high linearity is realized by using the passive capacitor error-averaging technique to calibrate the capacitor...A 13bit,pipelined analog-to-digital converter （ADC） designed to achieve high linearity is described. The high linearity is realized by using the passive capacitor error-averaging technique to calibrate the capacitor mismatch error, a gain-boosting opamp to minimize the finite gain error and gain nonlinearity,a bootstrapping switch to reduce the switch on-resistor nonlinearity, and an anti-disturb design to reduce the noise from the digital supply. This ADC is implemented in 0.18μm CMOS technology and occupies a die area of 3.2mm^2 , including pads. Measured performance includes - 0.18/ 0.15LSB of differential nonlinearity, -0.35/0.5LSB of integral nonlinearity, 75.7dB of signal-to-noise plus distortion ratio （SNDR） and 90. 5 dBc of spurious-free dynamic range （SFDR） for 2.4MHz input at 2.5MS/s. At full speed conversion （5MS/s） and for the same 2.4MHz input, the measured SNDR and SFDR are 73.7dB and 83.9 dBc, respectively. The power dissipation including output pad drivers is 21mW at 2.5MS/s and 34mW at 5MS/s,both at 2.7V supply.展开更多
A direct conversion CMOS DVB-S front-end employs a T-configuration variable attenuator,a single-to- differential low noise amplifier, and a low noise mixer. By innovative use of the attenuator, the linearity handling ...A direct conversion CMOS DVB-S front-end employs a T-configuration variable attenuator,a single-to- differential low noise amplifier, and a low noise mixer. By innovative use of the attenuator, the linearity handling ability of the system is dramatically improved. The system is designed and fabricated in SMIC 0.18 μm RF CMOS technology. The measurement data show that the front-end provides a total of more than 30rib dynamic range and a noise figure of 5dB in the wide frequency signal band. The prototype front-end consumes only 10mA and achieves an IIP3 of ＋ 20dBm.展开更多
Combining magnetic negative stiffness mechanism(NSM) in parallel with positive stiffness has been considered to be an effective approach to realize the quasi-zero stiffness(QZS) characteristic,thus resolving the contr...Combining magnetic negative stiffness mechanism(NSM) in parallel with positive stiffness has been considered to be an effective approach to realize the quasi-zero stiffness(QZS) characteristic,thus resolving the contradiction between high load capacity and(ultra-) low-frequency vibration isolation capability.However,the remarkable stiffness nonlinearity of common magnetic NSMs restricts the displacement region with reliable negative stiffness,resulting in considerable nonlinear behavior,poor vibration attenuation performance,and probable instability under large amplitude vibrations.A novel combined negative stiffness mechanism(CNSM) with attractive magnetic NSM(ANSM) and repulsive magnetic NSM(RNSM) in parallel is proposed in this paper.The stiffness nonlinearities of the ANSM and RNSM in the CNSM are counteracted through the parallel configuration such that the displacement region with reliable linear stiffness of the CNSM is widened by several times.An analytical model of the CNSM is established by the magnetic charge model and verified by simulation on ANSYS Maxwell.Parametric studies are then conducted to investigate the effects of design parameters on the stiffness characteristic,providing guidelines for the optimal design of the CNSM.Meanwhile,the stiffness and nonlinearity of the CNSM are compared with that of a single ANSM and RNSM.Static and dynamic experiments are finally conducted on the proposed test prototypes.Experimental results demonstrated the validity of the established model and the effectiveness of the CNSM in generating high linear stiffness within a wide displacement region and lowering the resonance frequency.Thus,the proposed CNSM can be applied in(ultra-) low-frequency vibration isolation under large amplitude excitations.展开更多
A high linearity 1.575 GHz SiGe：HBT low noise amplifier （LNA） for global positioning system applications is described. The bipolar cascoded with an MOSFET LNA was fabricated in a commercial 0.18 μm SiGe BiCMOS pro...A high linearity 1.575 GHz SiGe：HBT low noise amplifier （LNA） for global positioning system applications is described. The bipolar cascoded with an MOSFET LNA was fabricated in a commercial 0.18 μm SiGe BiCMOS process, A resistor bias feed circuit with a feedback resistor was designed for the LNA input transistor to improve its intermodulation and compression performance. The packaged chip tested on board has displayed a noise figure of 1. I 1 dB, a power gain of 18 dB, an output 1 dB compression point of ＋7.8 dBm and an input third-order intercept point of ＋1.8 dBm. The chip occupies a 500 × 560μm^2 area and consumes 3.6 mA from a 2.85 V power supply.展开更多
This paper presents a channel-select filter that employs an active-RC bi-quad structure for TV-tuner application. A design method to optimize the IIP3 of the bi-quad is developed. Multi-band selection and gain adjustm...This paper presents a channel-select filter that employs an active-RC bi-quad structure for TV-tuner application. A design method to optimize the IIP3 of the bi-quad is developed. Multi-band selection and gain adjustment are implemented using switching resistors in the resistor array and capacitors in the capacitor array. Q-factor degradation is compensated by a tuning segmented resistor. A feed-forward OTA with high gain and low third-order distortion is applied in the bi-quad to maximize linearity performance and minimize area by avoiding extra compensation capacitor use. An RC tuning circuit and DC offset cancellation circuit are designed to overcome the process variation and DC offset, respectively. The experimental results yield an in-band IIP3 of more than 31 dBm at 0 dB gain, a 54 dB gain range with 6 dB gain step, and a continuous frequency tuning range from 0.25 to 4 MHz. The in-band ripple is less than 1.4 dB at high gain mode, while the gain error and frequency tuning error are no more than 3.4% and 5%, respectively. The design, which is fabricated in a 0.18 μm CMOS process, consumes 12.6 mW power at a 1.8 V supply and occupies 1.28 mm2.展开更多
A 50 MHz-1 GHz low noise and high linearity amplifier monolithic-microwave integrated-circuit （MMIC） for cable TV is presented.A shunt AC voltage negative feedback combined with source current negative feedback is a...A 50 MHz-1 GHz low noise and high linearity amplifier monolithic-microwave integrated-circuit （MMIC） for cable TV is presented.A shunt AC voltage negative feedback combined with source current negative feedback is adopted to extend the bandwidth and linearity.A novel DC bias feedback is introduced to stabilize the operation point,which improved the linearity further.The circuit was fabricated with a 0.15μm InGaAs PHEMT （pseudomorphic high electron mobility transistor） process.The test was carried out in 75Ωsystems from 50 MHz to 1 GHz.The measurement results showed that it gave a small signal gain of 16.5 dB with little gain ripples of less than±1dB.An excellent noise figure of 1.7-2.9 dB is obtained in the designed band.The IIP3 is 16 dBm, which shows very good linearity.The CSO and CTB are high up to 68 dBc and 77 dBc,respectively.The chip area is 0.56 mm^2 and the power dissipation is 110 mA with a 5 V supply.It is ideally suited to cable TV systems.展开更多
A high linearity current communicating passive mixer including the mixing cell and transimpedance amplifier(TIA) is introduced.It employs the resistor in the TIA to reduce the source voltage and the gate voltage of th...A high linearity current communicating passive mixer including the mixing cell and transimpedance amplifier(TIA) is introduced.It employs the resistor in the TIA to reduce the source voltage and the gate voltage of the mixing cell.The optimum linearity and the maximum symmetric switching operation are obtained at the same time.The mixer is implemented in a 0.25μm CMOS process.The test shows that it achieves an input third-order intercept point of 13.32 dBm,conversion gain of 5.52 dB,and a single sideband noise figure of 20 dB.展开更多
A wideband large dynamic range and high linearity U-band RF front-end for mobile DTV is introduced, and includes a noise-cancelling low-noise amplifier （LNA）, an RF programmable gain amplifier （RFPGA） and a curren...A wideband large dynamic range and high linearity U-band RF front-end for mobile DTV is introduced, and includes a noise-cancelling low-noise amplifier （LNA）, an RF programmable gain amplifier （RFPGA） and a current communicating passive mixer. The noise/distortion cancelling structure and RC post-distortion compensation are employed to improve the linearity of the LNA. An RFPGA with five stages provides large dynamic range and fine gain resolution. A simple resistor voltage network in the passive mixer decreases the gate bias voltage of the mixing transistor, and optimum linearity and symmetrical mixing is obtained at the same time. The RF front-end is implemented in a 0.25 #m CMOS process. Tests show that it achieves an IIP3 （third-order intercept point） of -17 dBm, a conversion gain of 39 dB, and a noise figure of 5.8 dB. The RFPGA achieves a dynamic range of-36.2 to 23.5 dB with a resolution of 0.32 dB.展开更多
A high linearity current mode multiplier/divider （CMM/D） with a wide dynamic range is presented. The proposed CMM/D is based on the voltage-current characteristic of the diode, thus wide dynamic range is achieved. I...A high linearity current mode multiplier/divider （CMM/D） with a wide dynamic range is presented. The proposed CMM/D is based on the voltage-current characteristic of the diode, thus wide dynamic range is achieved. In addition, high linearity is achieved because high accuracy current mirrors are adopted and the output current is insensitive to the temperature and device parameters of the fabrication process. Furthermore, no extra bias current for all input signals is required and thus power saving is realized. With proper selection of establishing the input terminal, the proposed circuit can perform as a mulfifunction circuit to he operated as a multiplier/divider, without changing its topology. The proposed circuit is implemented in a 0.25μm BCD process and the chip area is 0.26 ~ 0.24 mm2. The simulation and measurement results show that the maximum static linearity error is 4-1.8% and the total harmonic distortion is 0.4% while the input current ranges from 0 to 200 μA.展开更多
A stray-insensitive symmetrical capacitance-to-voltage converter for capacitive sensors is presented. By introducing a reference branch,a symmetrical readout circuit is realized.The linear input range is increased, an...A stray-insensitive symmetrical capacitance-to-voltage converter for capacitive sensors is presented. By introducing a reference branch,a symmetrical readout circuit is realized.The linear input range is increased, and the systematic offsets of two input op-amps are cancelled.The common-mode noise and even-order distortion are also rejected.A chopper stabilization technique is adopted to further reduce the offset and flicker noise of the op-amps,and a Verilog-A-based varactor is used to model the real variable sensing capacitor.Simulation results show that the output voltage of this proposed readout circuit responds correctly,while the under-test capacitance changes with a frequency of 1 kHz.A metal-insulator-metal capacitor array is designed on chip for measurement, and the measurement results show that this circuit achieves sensitivity of 370 mV/pF,linearity error below 1%and power consumption as low as 2.5 mW.This symmetrical readout circuit can respond to an FPGA controlled sensing capacitor array changed every 1 ms.展开更多
A low noise, high conversion gain down-conversion mixer for WLAN 802.11a applications, which adopts the high intermediate frequency （IF） topology, is presented. The input radio frequency （RF）band, local oscillator...A low noise, high conversion gain down-conversion mixer for WLAN 802.11a applications, which adopts the high intermediate frequency （IF） topology, is presented. The input radio frequency （RF）band, local oscillator（LO）frequency band and output IF are 5.15 to 5.35, 4.15 to 4.35 and 1 GHz, respectively. Source resistive degeneration technique and pseudo-differential Gilbert topology are used to achieve high linearity, and, current bleeding technique and LC resonant loads are used to acquire a low noise figure. In addition, the mixer adopts a common-source transistor pair cross-stacked with a source follow pair（CSSF）circuit as an output buffer to enhance the mixer＇s conversion gain but not deteriorate the other performances. The mixer is implemented in 0.18 μm RF CMOS（complementary metal oxide semiconductor transistor）technology and the chip area of the mixer including all bonding pads is 580 μm×1 185 μm. The measured results show that under a 1.8 V supply, the conversion gain is 10.1 dB; the input 1 dB compression point and the input-referred third-order intercept point are-3.5 and 5.3 dBm, respectively; the single side band （SSB）noise figure （NF）is 8.65 dB, and the core current consumption is 3.8 mA.展开更多
High-linearity electro-optic(EO)modulators play a crucial role in microwave photonics(MWP).Although various methods have been explored to enhance linearity in MWP links,they are often constrained by the intrinsic nonl...High-linearity electro-optic(EO)modulators play a crucial role in microwave photonics(MWP).Although various methods have been explored to enhance linearity in MWP links,they are often constrained by the intrinsic nonlinearity of modulator materials,the complexity of external control devices,the bulkiness of structures,and bandwidth limitations.In this study,we present an integrated thin-film lithium niobate(TFLN)linear Mach–Zehnder modulator(LMZM),showing,to our knowledge,a record-high spurious-free dynamic range(SFDR)of 121.7 dB·Hz^(4∕5)at 1 GHz with an optical power(OP)of 5.5 dBm into the photodetector(PD),based on a widebandwidth(>50 GHz)dual-optical-mode(TE0 and TE1)co-modulated configuration with just one RF input.Additionally,compared to conventional MZMs(CMZMs),the LMZM exhibits a>10.6-dB enhancement in SFDR with an OP of>−8 dBm at 1 GHz,and maintains a 6.07-dB SFDR improvement even at 20 GHz with an OP of 0 dBm.The novel LMZM,featuring high linearity,wide bandwidth,structural simplicity,and high integration,holds significant potential as a key component in future large-scale and high-performance MWP integrated circuits.展开更多
Integrated high-linearity modulators are crucial for high dynamic-range microwave photonic(MWP)systems.Conventional linearization schemes usually involve the fine tuning of radio-frequency(RF)power distribution,which ...Integrated high-linearity modulators are crucial for high dynamic-range microwave photonic(MWP)systems.Conventional linearization schemes usually involve the fine tuning of radio-frequency(RF)power distribution,which is rather inconvenient for practical applications and can hardly be implemented on the integrated photonics chip.In this paper,we propose an elegant scheme to linearize a silicon-based modulator in which the active tuning of RF power is eliminated.The device consists of two carrier-depletion-based Mach-Zehnder modulators(MZMs),which are connected in series by a 1×2 thermal optical switch(OS).The OS is used to adjust the ratio between the modulation depths of the two sub-MZMs.Under a proper ratio,the complementary third-order intermodulation distortion(IMD3)of the two sub-MZMs can effectively cancel each other out.The measured spurious-free dynamic ranges for IMD3 are 131,127,118,110,and 109 d B·Hz^(6∕7)at frequencies of 1,10,20,30,and 40 GHz,respectively,which represent the highest linearities ever reached by the integrated modulator chips on all available material platforms.展开更多
A quadrature mixer with a shared transconductor stage is analyzed,including voltage conversion gain, linearity, noise figure, and image rejection. The analysis indicates it has better performance than a conventional G...A quadrature mixer with a shared transconductor stage is analyzed,including voltage conversion gain, linearity, noise figure, and image rejection. The analysis indicates it has better performance than a conventional Gilbert mixer pair in commutating mode. A quadrature down-conversion mixer based on this topology is designed and optimized for an ultra high frequency RFID reader. Operating in the 915MHz ISM band, the presented quadrature mixer measures a conversion gain of 12.5dB,an IIP3 of 10dBm, an IIP2 of 58dBm, and an SSB noise figure of 17.6riB. The chip was fabricated in a 0. 18μm 1P6M RF CMOS process and consumes only 3mA of current from a 1.8V power supply.展开更多
A three-stage 4.8-6 GHz monolithic power amplifier（PA） compatible with IEEE 802.11a/n designed based on an advanced 2μm InGaP/GaAs hetero-junction bipolar transistor（HBT） process is presented.The PA integrates in...A three-stage 4.8-6 GHz monolithic power amplifier（PA） compatible with IEEE 802.11a/n designed based on an advanced 2μm InGaP/GaAs hetero-junction bipolar transistor（HBT） process is presented.The PA integrates input matching and closed-loop power control circuits on chip.Under 3.3 V DC bias,the amplifier achieves a ~31 dB small signal gain,excellent wide band input and output matching among overall 1.2 GHz bandwidth,and up to 24.5 dBm linear output power below EVM 3%with IEEE 802.11a 64QAM OFDM input signal.展开更多
Sand cay is a special kind of islet formed by coral detritus and bioclast, which is common in Nansha Islands of China. Some sand cays play an important role in ocean strategy and economy, but surprisingly we know litt...Sand cay is a special kind of islet formed by coral detritus and bioclast, which is common in Nansha Islands of China. Some sand cays play an important role in ocean strategy and economy, but surprisingly we know little about them, especially those recently formed sand cays. In this research, we monitor migration of a new sand cay in Nanxun Jiao（Gaven Reef） using a series of Quick Bird and World View-2 satellite images between June 2006 and August 2013. We conduct a regression between migration distance and wind observational data to examine the migration patterns of the new sand cay. The migration distance is calculated based on the sand cay locations extracted based on Normalized Difference Water Index（NDWI）. The wind observational data downloaded from NOAA are reformed into four wind direction vectors. Based on the results of regression, we concluded that the migration of the new sand cay on Nanxun Jiao was significantly associated with the east, west and north wind.East wind was the main influence factor of the migration; its impact strength was almost twice as the west and north wind. The south wind has little effect on the migration of the sand cay, which is partly blocked by the artificial structure in the south.展开更多
This paper concerns computational problems of the concave penalized linear regression model.We propose a fixed point iterative algorithm to solve the computational problem based on the fact that the penalized estimato...This paper concerns computational problems of the concave penalized linear regression model.We propose a fixed point iterative algorithm to solve the computational problem based on the fact that the penalized estimator satisfies a fixed point equation.The convergence property of the proposed algorithm is established.Numerical studies are conducted to evaluate the finite sample performance of the proposed algorithm.展开更多
This paper focuses on synthesizing a mixed robust H_2/H_∞ linear parameter varying（LPV） controller for the longitudinal motion of an air-breathing hypersonic vehicle via a high order singular value decomposition（H...This paper focuses on synthesizing a mixed robust H_2/H_∞ linear parameter varying（LPV） controller for the longitudinal motion of an air-breathing hypersonic vehicle via a high order singular value decomposition（HOSVD） approach.The design of hypersonic flight control systems is highly challenging due to the enormous complexity of the vehicle dynamics and the presence of significant uncertainties.Motivated by recent results on both LPV control and tensor-product（TP） model transformation approach,the velocity and altitude tracking control problems for the air-breathing hypersonic vehicle is reduced to that of a state feedback stabilizing controller design for a polytopic LPV system with guaranteed performances.The controller implementation is converted into a convex optimization problem with parameterdependent linear matrix inequalities（LMIs） constraints,which is intuitively tractable using LMI control toolbox.Finally,numerical simulation results demonstrate the effectiveness of the proposed approach.展开更多
In the emerging 5G and beyond 5G(B5G)era,the spotlight is sharply focused on the power amplifier,a critical component with stringent specification requirements that dictates the performance of the transmitter.The gall...In the emerging 5G and beyond 5G(B5G)era,the spotlight is sharply focused on the power amplifier,a critical component with stringent specification requirements that dictates the performance of the transmitter.The gallium nitride(GaN)device,with its superior inherent properties,is surfacing as a front-runner for power amplifier applications.The increasing demand for high frequency,high linearity,and cost-effective GaN power amplifiers is driven by anticipated traffic surges and the need for extensive 5G deployment.This paper offers a thorough review and future perspective on research developments in RF GaN device technology.It encompasses critical issues in advanced device and circuit technology,with a focus on high frequency,high linearity,cost-effective GaN-on-Si high electron mobility transistors(HEMTs),and compact modeling.This work aims to serve as a guide for the utilization of GaN HEMTs in 5G communication applications.展开更多
文摘A 13bit,pipelined analog-to-digital converter （ADC） designed to achieve high linearity is described. The high linearity is realized by using the passive capacitor error-averaging technique to calibrate the capacitor mismatch error, a gain-boosting opamp to minimize the finite gain error and gain nonlinearity,a bootstrapping switch to reduce the switch on-resistor nonlinearity, and an anti-disturb design to reduce the noise from the digital supply. This ADC is implemented in 0.18μm CMOS technology and occupies a die area of 3.2mm^2 , including pads. Measured performance includes - 0.18/ 0.15LSB of differential nonlinearity, -0.35/0.5LSB of integral nonlinearity, 75.7dB of signal-to-noise plus distortion ratio （SNDR） and 90. 5 dBc of spurious-free dynamic range （SFDR） for 2.4MHz input at 2.5MS/s. At full speed conversion （5MS/s） and for the same 2.4MHz input, the measured SNDR and SFDR are 73.7dB and 83.9 dBc, respectively. The power dissipation including output pad drivers is 21mW at 2.5MS/s and 34mW at 5MS/s,both at 2.7V supply.
文摘A direct conversion CMOS DVB-S front-end employs a T-configuration variable attenuator,a single-to- differential low noise amplifier, and a low noise mixer. By innovative use of the attenuator, the linearity handling ability of the system is dramatically improved. The system is designed and fabricated in SMIC 0.18 μm RF CMOS technology. The measurement data show that the front-end provides a total of more than 30rib dynamic range and a noise figure of 5dB in the wide frequency signal band. The prototype front-end consumes only 10mA and achieves an IIP3 of ＋ 20dBm.
基金supported by the National Natural Science Foundation of China(Grant No.52075193)the National Key R&D Program of China(Grant Nos.2020YFB2007301 and 2020YFB2007601)+1 种基金China Postdoctoral Science Foundation(Grant No.2022M711250)the National Science and Technology Major Project of China(Grant No.2017ZX02101007-002)。
文摘Combining magnetic negative stiffness mechanism(NSM) in parallel with positive stiffness has been considered to be an effective approach to realize the quasi-zero stiffness(QZS) characteristic,thus resolving the contradiction between high load capacity and(ultra-) low-frequency vibration isolation capability.However,the remarkable stiffness nonlinearity of common magnetic NSMs restricts the displacement region with reliable negative stiffness,resulting in considerable nonlinear behavior,poor vibration attenuation performance,and probable instability under large amplitude vibrations.A novel combined negative stiffness mechanism(CNSM) with attractive magnetic NSM(ANSM) and repulsive magnetic NSM(RNSM) in parallel is proposed in this paper.The stiffness nonlinearities of the ANSM and RNSM in the CNSM are counteracted through the parallel configuration such that the displacement region with reliable linear stiffness of the CNSM is widened by several times.An analytical model of the CNSM is established by the magnetic charge model and verified by simulation on ANSYS Maxwell.Parametric studies are then conducted to investigate the effects of design parameters on the stiffness characteristic,providing guidelines for the optimal design of the CNSM.Meanwhile,the stiffness and nonlinearity of the CNSM are compared with that of a single ANSM and RNSM.Static and dynamic experiments are finally conducted on the proposed test prototypes.Experimental results demonstrated the validity of the established model and the effectiveness of the CNSM in generating high linear stiffness within a wide displacement region and lowering the resonance frequency.Thus,the proposed CNSM can be applied in(ultra-) low-frequency vibration isolation under large amplitude excitations.
文摘A high linearity 1.575 GHz SiGe：HBT low noise amplifier （LNA） for global positioning system applications is described. The bipolar cascoded with an MOSFET LNA was fabricated in a commercial 0.18 μm SiGe BiCMOS process, A resistor bias feed circuit with a feedback resistor was designed for the LNA input transistor to improve its intermodulation and compression performance. The packaged chip tested on board has displayed a noise figure of 1. I 1 dB, a power gain of 18 dB, an output 1 dB compression point of ＋7.8 dBm and an input third-order intercept point of ＋1.8 dBm. The chip occupies a 500 × 560μm^2 area and consumes 3.6 mA from a 2.85 V power supply.
文摘This paper presents a channel-select filter that employs an active-RC bi-quad structure for TV-tuner application. A design method to optimize the IIP3 of the bi-quad is developed. Multi-band selection and gain adjustment are implemented using switching resistors in the resistor array and capacitors in the capacitor array. Q-factor degradation is compensated by a tuning segmented resistor. A feed-forward OTA with high gain and low third-order distortion is applied in the bi-quad to maximize linearity performance and minimize area by avoiding extra compensation capacitor use. An RC tuning circuit and DC offset cancellation circuit are designed to overcome the process variation and DC offset, respectively. The experimental results yield an in-band IIP3 of more than 31 dBm at 0 dB gain, a 54 dB gain range with 6 dB gain step, and a continuous frequency tuning range from 0.25 to 4 MHz. The in-band ripple is less than 1.4 dB at high gain mode, while the gain error and frequency tuning error are no more than 3.4% and 5%, respectively. The design, which is fabricated in a 0.18 μm CMOS process, consumes 12.6 mW power at a 1.8 V supply and occupies 1.28 mm2.
文摘A 50 MHz-1 GHz low noise and high linearity amplifier monolithic-microwave integrated-circuit （MMIC） for cable TV is presented.A shunt AC voltage negative feedback combined with source current negative feedback is adopted to extend the bandwidth and linearity.A novel DC bias feedback is introduced to stabilize the operation point,which improved the linearity further.The circuit was fabricated with a 0.15μm InGaAs PHEMT （pseudomorphic high electron mobility transistor） process.The test was carried out in 75Ωsystems from 50 MHz to 1 GHz.The measurement results showed that it gave a small signal gain of 16.5 dB with little gain ripples of less than±1dB.An excellent noise figure of 1.7-2.9 dB is obtained in the designed band.The IIP3 is 16 dBm, which shows very good linearity.The CSO and CTB are high up to 68 dBc and 77 dBc,respectively.The chip area is 0.56 mm^2 and the power dissipation is 110 mA with a 5 V supply.It is ideally suited to cable TV systems.
基金supported by the National High Technology R&D Program ofChina(No.2011AA040102)the National Science and Technology Major Project ofthe Ministry of Science and Technology of China(No.2009ZX01031-002-008-002)
文摘A high linearity current communicating passive mixer including the mixing cell and transimpedance amplifier(TIA) is introduced.It employs the resistor in the TIA to reduce the source voltage and the gate voltage of the mixing cell.The optimum linearity and the maximum symmetric switching operation are obtained at the same time.The mixer is implemented in a 0.25μm CMOS process.The test shows that it achieves an input third-order intercept point of 13.32 dBm,conversion gain of 5.52 dB,and a single sideband noise figure of 20 dB.
基金supported by the National High-Tech R&D Program of China(No.2011AA040102)the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2009ZX01031-002-008-002)
文摘A wideband large dynamic range and high linearity U-band RF front-end for mobile DTV is introduced, and includes a noise-cancelling low-noise amplifier （LNA）, an RF programmable gain amplifier （RFPGA） and a current communicating passive mixer. The noise/distortion cancelling structure and RC post-distortion compensation are employed to improve the linearity of the LNA. An RFPGA with five stages provides large dynamic range and fine gain resolution. A simple resistor voltage network in the passive mixer decreases the gate bias voltage of the mixing transistor, and optimum linearity and symmetrical mixing is obtained at the same time. The RF front-end is implemented in a 0.25 #m CMOS process. Tests show that it achieves an IIP3 （third-order intercept point） of -17 dBm, a conversion gain of 39 dB, and a noise figure of 5.8 dB. The RFPGA achieves a dynamic range of-36.2 to 23.5 dB with a resolution of 0.32 dB.
基金Project supported by the Important National S&T Special Project of China(Nos.2009ZX01031-003-003,51308020305)
文摘A high linearity current mode multiplier/divider （CMM/D） with a wide dynamic range is presented. The proposed CMM/D is based on the voltage-current characteristic of the diode, thus wide dynamic range is achieved. In addition, high linearity is achieved because high accuracy current mirrors are adopted and the output current is insensitive to the temperature and device parameters of the fabrication process. Furthermore, no extra bias current for all input signals is required and thus power saving is realized. With proper selection of establishing the input terminal, the proposed circuit can perform as a mulfifunction circuit to he operated as a multiplier/divider, without changing its topology. The proposed circuit is implemented in a 0.25μm BCD process and the chip area is 0.26 ~ 0.24 mm2. The simulation and measurement results show that the maximum static linearity error is 4-1.8% and the total harmonic distortion is 0.4% while the input current ranges from 0 to 200 μA.
文摘A stray-insensitive symmetrical capacitance-to-voltage converter for capacitive sensors is presented. By introducing a reference branch,a symmetrical readout circuit is realized.The linear input range is increased, and the systematic offsets of two input op-amps are cancelled.The common-mode noise and even-order distortion are also rejected.A chopper stabilization technique is adopted to further reduce the offset and flicker noise of the op-amps,and a Verilog-A-based varactor is used to model the real variable sensing capacitor.Simulation results show that the output voltage of this proposed readout circuit responds correctly,while the under-test capacitance changes with a frequency of 1 kHz.A metal-insulator-metal capacitor array is designed on chip for measurement, and the measurement results show that this circuit achieves sensitivity of 370 mV/pF,linearity error below 1%and power consumption as low as 2.5 mW.This symmetrical readout circuit can respond to an FPGA controlled sensing capacitor array changed every 1 ms.
基金The Science and Technology Program of Zhejiang Province (No.2008C16017)
文摘A low noise, high conversion gain down-conversion mixer for WLAN 802.11a applications, which adopts the high intermediate frequency （IF） topology, is presented. The input radio frequency （RF）band, local oscillator（LO）frequency band and output IF are 5.15 to 5.35, 4.15 to 4.35 and 1 GHz, respectively. Source resistive degeneration technique and pseudo-differential Gilbert topology are used to achieve high linearity, and, current bleeding technique and LC resonant loads are used to acquire a low noise figure. In addition, the mixer adopts a common-source transistor pair cross-stacked with a source follow pair（CSSF）circuit as an output buffer to enhance the mixer＇s conversion gain but not deteriorate the other performances. The mixer is implemented in 0.18 μm RF CMOS（complementary metal oxide semiconductor transistor）technology and the chip area of the mixer including all bonding pads is 580 μm×1 185 μm. The measured results show that under a 1.8 V supply, the conversion gain is 10.1 dB; the input 1 dB compression point and the input-referred third-order intercept point are-3.5 and 5.3 dBm, respectively; the single side band （SSB）noise figure （NF）is 8.65 dB, and the core current consumption is 3.8 mA.
基金National Natural Science Foundation of China(62405383)Basic and Applied Basic Research Foundation of Guangdong Province(2023A1515110666)+2 种基金Guangdong Introducing Innovative and Entrepreneurial Teams of“The Pearl River Talent Recruitment Program”(2021ZT09X044)Innovation Program for Quantum Science and Technology(2021ZD0301500)Innovation Program for Quantum Science and Technology(2021ZD0300700)。
文摘High-linearity electro-optic(EO)modulators play a crucial role in microwave photonics(MWP).Although various methods have been explored to enhance linearity in MWP links,they are often constrained by the intrinsic nonlinearity of modulator materials,the complexity of external control devices,the bulkiness of structures,and bandwidth limitations.In this study,we present an integrated thin-film lithium niobate(TFLN)linear Mach–Zehnder modulator(LMZM),showing,to our knowledge,a record-high spurious-free dynamic range(SFDR)of 121.7 dB·Hz^(4∕5)at 1 GHz with an optical power(OP)of 5.5 dBm into the photodetector(PD),based on a widebandwidth(>50 GHz)dual-optical-mode(TE0 and TE1)co-modulated configuration with just one RF input.Additionally,compared to conventional MZMs(CMZMs),the LMZM exhibits a>10.6-dB enhancement in SFDR with an OP of>−8 dBm at 1 GHz,and maintains a 6.07-dB SFDR improvement even at 20 GHz with an OP of 0 dBm.The novel LMZM,featuring high linearity,wide bandwidth,structural simplicity,and high integration,holds significant potential as a key component in future large-scale and high-performance MWP integrated circuits.
基金National Natural Science Foundation of China(62305303,62205164)Science and Technology Plan Project of Zhejiang(2022C01108)。
文摘Integrated high-linearity modulators are crucial for high dynamic-range microwave photonic(MWP)systems.Conventional linearization schemes usually involve the fine tuning of radio-frequency(RF)power distribution,which is rather inconvenient for practical applications and can hardly be implemented on the integrated photonics chip.In this paper,we propose an elegant scheme to linearize a silicon-based modulator in which the active tuning of RF power is eliminated.The device consists of two carrier-depletion-based Mach-Zehnder modulators(MZMs),which are connected in series by a 1×2 thermal optical switch(OS).The OS is used to adjust the ratio between the modulation depths of the two sub-MZMs.Under a proper ratio,the complementary third-order intermodulation distortion(IMD3)of the two sub-MZMs can effectively cancel each other out.The measured spurious-free dynamic ranges for IMD3 are 131,127,118,110,and 109 d B·Hz^(6∕7)at frequencies of 1,10,20,30,and 40 GHz,respectively,which represent the highest linearities ever reached by the integrated modulator chips on all available material platforms.
文摘A quadrature mixer with a shared transconductor stage is analyzed,including voltage conversion gain, linearity, noise figure, and image rejection. The analysis indicates it has better performance than a conventional Gilbert mixer pair in commutating mode. A quadrature down-conversion mixer based on this topology is designed and optimized for an ultra high frequency RFID reader. Operating in the 915MHz ISM band, the presented quadrature mixer measures a conversion gain of 12.5dB,an IIP3 of 10dBm, an IIP2 of 58dBm, and an SSB noise figure of 17.6riB. The chip was fabricated in a 0. 18μm 1P6M RF CMOS process and consumes only 3mA of current from a 1.8V power supply.
文摘A three-stage 4.8-6 GHz monolithic power amplifier（PA） compatible with IEEE 802.11a/n designed based on an advanced 2μm InGaP/GaAs hetero-junction bipolar transistor（HBT） process is presented.The PA integrates input matching and closed-loop power control circuits on chip.Under 3.3 V DC bias,the amplifier achieves a ~31 dB small signal gain,excellent wide band input and output matching among overall 1.2 GHz bandwidth,and up to 24.5 dBm linear output power below EVM 3%with IEEE 802.11a 64QAM OFDM input signal.
基金National Sea Islands Protection and Management Programme
文摘Sand cay is a special kind of islet formed by coral detritus and bioclast, which is common in Nansha Islands of China. Some sand cays play an important role in ocean strategy and economy, but surprisingly we know little about them, especially those recently formed sand cays. In this research, we monitor migration of a new sand cay in Nanxun Jiao（Gaven Reef） using a series of Quick Bird and World View-2 satellite images between June 2006 and August 2013. We conduct a regression between migration distance and wind observational data to examine the migration patterns of the new sand cay. The migration distance is calculated based on the sand cay locations extracted based on Normalized Difference Water Index（NDWI）. The wind observational data downloaded from NOAA are reformed into four wind direction vectors. Based on the results of regression, we concluded that the migration of the new sand cay on Nanxun Jiao was significantly associated with the east, west and north wind.East wind was the main influence factor of the migration; its impact strength was almost twice as the west and north wind. The south wind has little effect on the migration of the sand cay, which is partly blocked by the artificial structure in the south.
基金Supported by the National Natural Science Foundation of China(11701571)
文摘This paper concerns computational problems of the concave penalized linear regression model.We propose a fixed point iterative algorithm to solve the computational problem based on the fact that the penalized estimator satisfies a fixed point equation.The convergence property of the proposed algorithm is established.Numerical studies are conducted to evaluate the finite sample performance of the proposed algorithm.
基金supported by the National Natural Science Foundation of China(6120300761304239+1 种基金61503392)the Natural Science Foundation of Shaanxi Province(2015JQ6213)
文摘This paper focuses on synthesizing a mixed robust H_2/H_∞ linear parameter varying（LPV） controller for the longitudinal motion of an air-breathing hypersonic vehicle via a high order singular value decomposition（HOSVD） approach.The design of hypersonic flight control systems is highly challenging due to the enormous complexity of the vehicle dynamics and the presence of significant uncertainties.Motivated by recent results on both LPV control and tensor-product（TP） model transformation approach,the velocity and altitude tracking control problems for the air-breathing hypersonic vehicle is reduced to that of a state feedback stabilizing controller design for a polytopic LPV system with guaranteed performances.The controller implementation is converted into a convex optimization problem with parameterdependent linear matrix inequalities（LMIs） constraints,which is intuitively tractable using LMI control toolbox.Finally,numerical simulation results demonstrate the effectiveness of the proposed approach.
基金supported by the National Natural Science Foundation of China(62234009,62090014,62404165,and 62474135)the Natural Science Basic Research Program of Shaanxi(2024JC-YBQN-0611)+3 种基金the Stanford Graduate Fellowship(SGF)the China Postdoctoral Science Foundation(2023M732730)Postdoctoral Fellowship Program of CPSF(GZB20230557)the Fundamental Research Funds for the Central Universities of China(XJSJ23056,XJSJ23047,andZDRC2002).
文摘In the emerging 5G and beyond 5G(B5G)era,the spotlight is sharply focused on the power amplifier,a critical component with stringent specification requirements that dictates the performance of the transmitter.The gallium nitride(GaN)device,with its superior inherent properties,is surfacing as a front-runner for power amplifier applications.The increasing demand for high frequency,high linearity,and cost-effective GaN power amplifiers is driven by anticipated traffic surges and the need for extensive 5G deployment.This paper offers a thorough review and future perspective on research developments in RF GaN device technology.It encompasses critical issues in advanced device and circuit technology,with a focus on high frequency,high linearity,cost-effective GaN-on-Si high electron mobility transistors(HEMTs),and compact modeling.This work aims to serve as a guide for the utilization of GaN HEMTs in 5G communication applications.
