Small signal equivalent circuit model and modulation properties of vertical cavity surface emitting lasers(VCSEL's) are presented.The modulation properties both in analytic equation calculation and in circuit mo...Small signal equivalent circuit model and modulation properties of vertical cavity surface emitting lasers(VCSEL's) are presented.The modulation properties both in analytic equation calculation and in circuit model simulation are studied.The analytic equation calculation of the modulation properties is calculated by using Mathcad program and the circuit model simulation is simulated by using Pspice program respectively.The results of calculation and the simulation are in good agreement with each other.Experiment is performed to testify the circuit model.展开更多
For the high resolution required in a digital interface circuit of an accelerometer used in feeble gravity measurement, a switched-capacitor （SC） sigma-delta modulator （SDM） is proposed. Based on the principle and...For the high resolution required in a digital interface circuit of an accelerometer used in feeble gravity measurement, a switched-capacitor （SC） sigma-delta modulator （SDM） is proposed. Based on the principle and the topology structure of the SDMs, the influence of oversampling ratio, bits of an internal quantizer and the cascaded structure on weak signal detecting precision is analyzed, and an ideal low-distortion SDM with a second-order 1-bit structure satisfying the high- resolution interface circuit of an accelerometer is designed. With the research on non-idealities of each SDM block in the SC circuit implementation and their impacts on power consumption, the realized parameters of low-power SDMs based on different bandwidths are devised and the power consumption of each SDM is estimated. Time-domain behavioral simulation is explored based on Simulink. The results demonstrate that a 21- bit resolution of the designed SDMs can be achieved on the premise of low power, and the parameters for the circuit implementation can be directed to the transistor-level circuit design.展开更多
We present a new hybrid digital pulse-width modulator （DPWM） for digital DC-DC converters that employs a ring-oscillator/counter structure. Based on a temperature/process compensation technique and a novel digital c...We present a new hybrid digital pulse-width modulator （DPWM） for digital DC-DC converters that employs a ring-oscillator/counter structure. Based on a temperature/process compensation technique and a novel digital controller, the proposed DPWM can not only offer temperature/process-independent pulse widths, but also operate at a much higher clock frequency than the existing delay-line/counter DPWM structure. Post-simulation results show that with our DPWM, the system clock frequency reaches 156.9MHz while the worst variation,in a temperature range of 0 to 100℃under all process corners,is only± 9.4%.展开更多
We propose a novel thermal-conscious power model for integrated circuits that can accurately predict power and temperature under voltage scaling. Experimental results show that the leakage power consumption is underes...We propose a novel thermal-conscious power model for integrated circuits that can accurately predict power and temperature under voltage scaling. Experimental results show that the leakage power consumption is underestimated by 52 % if thermal effects are omitted. Furthermore, an inconsistency arises when energy and temperature are simultaneously optimized by dynamic voltage scaling. Temperature is a limiting factor for future integrated circuits,and the thermal optimization approach can attain a temperature reduction of up to 12℃ with less than 1.8% energy penalty compared with the energy optimization one.展开更多
An accurate 1.08GHz CMOS LC voltage-controlled oscillator is implemented in a 0.35μm standard 2P4M CMOS process.A new convenient method of calculating oscillator period is presented.With this period calculation tech...An accurate 1.08GHz CMOS LC voltage-controlled oscillator is implemented in a 0.35μm standard 2P4M CMOS process.A new convenient method of calculating oscillator period is presented.With this period calculation technique,the frequency tuning curves agree well with the experiment.At a 3.3V supply,the LC-VCO measures a phase noise of -82.2dBc/Hz at a 10kHz frequency offset while dissipating 3.1mA current.The chip size is 0.86mm×0.82mm.展开更多
An accurate circuit model of the microwave small signal characteristics of AlGaAs/GaAs HBT (heterojunction bipolar transistor) is extremely useful for microwave linear applications of the device. This paper presents ...An accurate circuit model of the microwave small signal characteristics of AlGaAs/GaAs HBT (heterojunction bipolar transistor) is extremely useful for microwave linear applications of the device. This paper presents a small signal AlGaAs/GaAs HBT equivalent circuit, based on the DC characteristics and S parameter of the device. Using Volterra series, we have calculated the third order intermodulation distortion in a linear AlGaAs/GaAs HBT amplifier. The calculations are well concordant with the measurements from two tone signals intermodulation distortion test, and its excellent third order intermodulation performance shows that AlGaAs/GaAs HBT is a very attractive candidate for linear amplification.展开更多
A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used ...A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used to improve the linearity of the quadrature modulator;An LC resonant tank is used as the load of the upconversion mixer to improve its gain and increase the voltage swing. The measurement results show that the input P1dB achieves -3.6dBm, the transducer power gain of the circuit is -3.6dB,and the current consumes about 45.8mA with a 1.8V power supply.展开更多
A water loop variable refrigerant flow（WLVRF）air-conditioning system is designed to be applied in large-scale buildings in northern China.The system is energy saving and it is an integrated system consisting of a va...A water loop variable refrigerant flow（WLVRF）air-conditioning system is designed to be applied in large-scale buildings in northern China.The system is energy saving and it is an integrated system consisting of a variable refrigerant flow（VRF）air-conditioning unit,a water loop and an air source heat pump.The water loop transports energy among different regions in the buildings instead of refrigerant pipes,decreasing the scale of the VRF air-conditioning unit and improving the performance.Previous models for refrigerants and building loads are cited in this investigation.Mathematical models of major equipment and other elements of the system are established using the lumped parameter method based on the DATAFIT software and the MATLAB software.The performance of the WLVRF system is simulated.The initial investments and the running costs are calculated based on the results of market research.Finally,a contrast is carried out between the WLVRF system and the traditional VRF system.The results show that the WLVRF system has a better working condition and lower running costs than the traditional VRF system.展开更多
A 10Gb/s transmitter module containing an electroabsorption modulator monolithically integrated with a distributed feedback (DFB) semiconductor laser is fabricated using the identical epitaxial layer scheme.Gain-coupl...A 10Gb/s transmitter module containing an electroabsorption modulator monolithically integrated with a distributed feedback (DFB) semiconductor laser is fabricated using the identical epitaxial layer scheme.Gain-coupling mechanism is employed to improve the single mode yield of the DFB laser,while inductively coupled plasma dry etching technique is utilized to reduce the modulator capacitance.The integrated device exhibits a threshold current as low as 12mA and an extinction ratio over 15dB at -2V bias.The small signal modulation bandwidth is measured to be over 10GHz.The transmission experiment at 10Gb/s indicates a power penalty less than 1dB at a bit-error-rate of 10 -12 after transmission through 35km single mode fiber.展开更多
Resonant dc link inverter is a zero voltage switching inverter.This paper proposes a new cascade resonant dc link inverter that consists of two power converter units,a rugged resonant dc link and an inverter bridge.A ...Resonant dc link inverter is a zero voltage switching inverter.This paper proposes a new cascade resonant dc link inverter that consists of two power converter units,a rugged resonant dc link and an inverter bridge.A detailed analysis of the soft switching process in the rugged resonant dc link and the realization of pulse width modulation (PWM) control strategy in the inverter bridge are presented in the paper. The operation modes, the input and output features and the interface between the rugged resonant dc link and the inverter bridge are also discussed. The relationship between the circuit features and the parameters is deduced, which provides a theoretical base for the circuit design. The analysis results show that the rugged resonant dc link can be regulated by open-loop control and the control of the rugged resonant dc link is independent of that of the inverter bridge, which makes the inverter control easy and realizable.The circuit of the inverter is simulated with a standard circuit simulation program PSPICE. The simulation results are corresponding to the predicted ones of the circuit analysis.展开更多
The performance of an OFDM/OQAM system under phase noise is analyzed. The analysis helps to direct the design of low cost tuners through specifying the required phase noise characteristics. Discrete time formulation o...The performance of an OFDM/OQAM system under phase noise is analyzed. The analysis helps to direct the design of low cost tuners through specifying the required phase noise characteristics. Discrete time formulation of OFDM/OQAM is first derived with the square root raised cosine (SRRC) filter as the pulse-shaping filter. Then the effect of multiplicative phase noise is equivalently represented as additive white Gaussian noise (AWGN), the variance of which is given analytically. We can observe that the same result as OFDM/QAM system is derived. Lastly, all the analytical results are verified by the bit error rate (BER) degradation through Monte Carlo simulation.展开更多
A new coarse tuning loop for a wide-band dual-loop frequency synthesizer is presented. The coarse tuning structure is composed of two digital modules, including a successive approximation register and a frequency comp...A new coarse tuning loop for a wide-band dual-loop frequency synthesizer is presented. The coarse tuning structure is composed of two digital modules, including a successive approximation register and a frequency comparator with a novel structure. The frequency comparator counts the prescaler cycles within a certain reference time and compares the number with preset data to estimate the VCO frequency. The frequency comparison error is analyzed in detail. Within a given coarse tuning time,our proposed structure shows a comparison error 20 times smaller than that of other reported structures. This structure also reuses the programmable divider as a part of the coarse tuning loop so that the circuit is greatly simplified.展开更多
文摘Small signal equivalent circuit model and modulation properties of vertical cavity surface emitting lasers(VCSEL's) are presented.The modulation properties both in analytic equation calculation and in circuit model simulation are studied.The analytic equation calculation of the modulation properties is calculated by using Mathcad program and the circuit model simulation is simulated by using Pspice program respectively.The results of calculation and the simulation are in good agreement with each other.Experiment is performed to testify the circuit model.
基金The National High Technology Research and Development Program of China (863 Program) ( No. 2006AA12Z302)
文摘For the high resolution required in a digital interface circuit of an accelerometer used in feeble gravity measurement, a switched-capacitor （SC） sigma-delta modulator （SDM） is proposed. Based on the principle and the topology structure of the SDMs, the influence of oversampling ratio, bits of an internal quantizer and the cascaded structure on weak signal detecting precision is analyzed, and an ideal low-distortion SDM with a second-order 1-bit structure satisfying the high- resolution interface circuit of an accelerometer is designed. With the research on non-idealities of each SDM block in the SC circuit implementation and their impacts on power consumption, the realized parameters of low-power SDMs based on different bandwidths are devised and the power consumption of each SDM is estimated. Time-domain behavioral simulation is explored based on Simulink. The results demonstrate that a 21- bit resolution of the designed SDMs can be achieved on the premise of low power, and the parameters for the circuit implementation can be directed to the transistor-level circuit design.
文摘We present a new hybrid digital pulse-width modulator （DPWM） for digital DC-DC converters that employs a ring-oscillator/counter structure. Based on a temperature/process compensation technique and a novel digital controller, the proposed DPWM can not only offer temperature/process-independent pulse widths, but also operate at a much higher clock frequency than the existing delay-line/counter DPWM structure. Post-simulation results show that with our DPWM, the system clock frequency reaches 156.9MHz while the worst variation,in a temperature range of 0 to 100℃under all process corners,is only± 9.4%.
文摘We propose a novel thermal-conscious power model for integrated circuits that can accurately predict power and temperature under voltage scaling. Experimental results show that the leakage power consumption is underestimated by 52 % if thermal effects are omitted. Furthermore, an inconsistency arises when energy and temperature are simultaneously optimized by dynamic voltage scaling. Temperature is a limiting factor for future integrated circuits,and the thermal optimization approach can attain a temperature reduction of up to 12℃ with less than 1.8% energy penalty compared with the energy optimization one.
文摘An accurate 1.08GHz CMOS LC voltage-controlled oscillator is implemented in a 0.35μm standard 2P4M CMOS process.A new convenient method of calculating oscillator period is presented.With this period calculation technique,the frequency tuning curves agree well with the experiment.At a 3.3V supply,the LC-VCO measures a phase noise of -82.2dBc/Hz at a 10kHz frequency offset while dissipating 3.1mA current.The chip size is 0.86mm×0.82mm.
文摘An accurate circuit model of the microwave small signal characteristics of AlGaAs/GaAs HBT (heterojunction bipolar transistor) is extremely useful for microwave linear applications of the device. This paper presents a small signal AlGaAs/GaAs HBT equivalent circuit, based on the DC characteristics and S parameter of the device. Using Volterra series, we have calculated the third order intermodulation distortion in a linear AlGaAs/GaAs HBT amplifier. The calculations are well concordant with the measurements from two tone signals intermodulation distortion test, and its excellent third order intermodulation performance shows that AlGaAs/GaAs HBT is a very attractive candidate for linear amplification.
文摘A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used to improve the linearity of the quadrature modulator;An LC resonant tank is used as the load of the upconversion mixer to improve its gain and increase the voltage swing. The measurement results show that the input P1dB achieves -3.6dBm, the transducer power gain of the circuit is -3.6dB,and the current consumes about 45.8mA with a 1.8V power supply.
文摘A water loop variable refrigerant flow（WLVRF）air-conditioning system is designed to be applied in large-scale buildings in northern China.The system is energy saving and it is an integrated system consisting of a variable refrigerant flow（VRF）air-conditioning unit,a water loop and an air source heat pump.The water loop transports energy among different regions in the buildings instead of refrigerant pipes,decreasing the scale of the VRF air-conditioning unit and improving the performance.Previous models for refrigerants and building loads are cited in this investigation.Mathematical models of major equipment and other elements of the system are established using the lumped parameter method based on the DATAFIT software and the MATLAB software.The performance of the WLVRF system is simulated.The initial investments and the running costs are calculated based on the results of market research.Finally,a contrast is carried out between the WLVRF system and the traditional VRF system.The results show that the WLVRF system has a better working condition and lower running costs than the traditional VRF system.
文摘A 10Gb/s transmitter module containing an electroabsorption modulator monolithically integrated with a distributed feedback (DFB) semiconductor laser is fabricated using the identical epitaxial layer scheme.Gain-coupling mechanism is employed to improve the single mode yield of the DFB laser,while inductively coupled plasma dry etching technique is utilized to reduce the modulator capacitance.The integrated device exhibits a threshold current as low as 12mA and an extinction ratio over 15dB at -2V bias.The small signal modulation bandwidth is measured to be over 10GHz.The transmission experiment at 10Gb/s indicates a power penalty less than 1dB at a bit-error-rate of 10 -12 after transmission through 35km single mode fiber.
文摘Resonant dc link inverter is a zero voltage switching inverter.This paper proposes a new cascade resonant dc link inverter that consists of two power converter units,a rugged resonant dc link and an inverter bridge.A detailed analysis of the soft switching process in the rugged resonant dc link and the realization of pulse width modulation (PWM) control strategy in the inverter bridge are presented in the paper. The operation modes, the input and output features and the interface between the rugged resonant dc link and the inverter bridge are also discussed. The relationship between the circuit features and the parameters is deduced, which provides a theoretical base for the circuit design. The analysis results show that the rugged resonant dc link can be regulated by open-loop control and the control of the rugged resonant dc link is independent of that of the inverter bridge, which makes the inverter control easy and realizable.The circuit of the inverter is simulated with a standard circuit simulation program PSPICE. The simulation results are corresponding to the predicted ones of the circuit analysis.
文摘The performance of an OFDM/OQAM system under phase noise is analyzed. The analysis helps to direct the design of low cost tuners through specifying the required phase noise characteristics. Discrete time formulation of OFDM/OQAM is first derived with the square root raised cosine (SRRC) filter as the pulse-shaping filter. Then the effect of multiplicative phase noise is equivalently represented as additive white Gaussian noise (AWGN), the variance of which is given analytically. We can observe that the same result as OFDM/QAM system is derived. Lastly, all the analytical results are verified by the bit error rate (BER) degradation through Monte Carlo simulation.
文摘A new coarse tuning loop for a wide-band dual-loop frequency synthesizer is presented. The coarse tuning structure is composed of two digital modules, including a successive approximation register and a frequency comparator with a novel structure. The frequency comparator counts the prescaler cycles within a certain reference time and compares the number with preset data to estimate the VCO frequency. The frequency comparison error is analyzed in detail. Within a given coarse tuning time,our proposed structure shows a comparison error 20 times smaller than that of other reported structures. This structure also reuses the programmable divider as a part of the coarse tuning loop so that the circuit is greatly simplified.
