A novel three layers microstrip antenna element that has the advantages of wideband and high-gain is proposed. The eigenvalue equation and the frequency characteristic formulas of the input Voltage Stand Wave Ratio ( ...A novel three layers microstrip antenna element that has the advantages of wideband and high-gain is proposed. The eigenvalue equation and the frequency characteristic formulas of the input Voltage Stand Wave Ratio ( VSWR ) are obtained by using the spectral domain method and equivalent circuit method, respectively. With the aid of the numerical results, a C-band microstrip antenna element with bandwidth of 16% (VSWR【1.5) or 25% (VSWR【2) and gain of 10.2-11.3 dB is developed, which are much larger than the bandwidth of 5-6% and the gain of 6-7 dB of the common microstrip antenna element.展开更多
The electric and magnetic energy distributions in photonic crystals （PC） are calculated by using the plane wave expansion （PWE） method. Even though the total electric and magnetic energy in each unit cell of photo...The electric and magnetic energy distributions in photonic crystals （PC） are calculated by using the plane wave expansion （PWE） method. Even though the total electric and magnetic energy in each unit cell of photonic crystals are equal to each other, the ratio of electric and magnetic energy densities varies depending on the local position. Based on Fermi＇s golden rule, the optical gain is analysed in the full quantum framework that takes the nonuniform energy density ratio into account. This nonuniform energy density ratio in photonic crystals, defined in an equal form as gain modification factor, leads to spatially inhomogeneous modification of optical gain. Results reported in the paper provide a new perspective for analysing gain characteristics, as well as the lasing properties, in photonic crystals.展开更多
The paper presents a fully integrated ultra-wide band(UWB)low noise amplifier(LNA)for 3-10 GHz applications.It employs self-biased resistive-feedback and current-reused technique to achieve wide input matching and low...The paper presents a fully integrated ultra-wide band(UWB)low noise amplifier(LNA)for 3-10 GHz applications.It employs self-biased resistive-feedback and current-reused technique to achieve wide input matching and low power characteristics.An improved biased architecture is adopted in the second stage to attain a better gain-compensation performance.The design is verified with TSMC standard 1 P6 M 0.18μm RF CMOS process.The measurement results show that the parasitic problem of the transistors at high frequencies is solved.A high and flat S21 of 9.7±1.5 dB and the lowest NF 3.5 dB are achieved in the desired frequency band.The power consumption is only 7.5 mA under 1.6 V supply.The proposed LNA achieves broadband flat gain,low noise,and high linearity performance simultaneously,allowing it to be used in 3-10 GHz UWB applications.展开更多
This paper proposes third order tunable bandwidth active Switched-Capacitor filter. The circuit consists of only op-amps and switched capacitors. The circuit is designed for circuit merit factor Q = 10. The proposed c...This paper proposes third order tunable bandwidth active Switched-Capacitor filter. The circuit consists of only op-amps and switched capacitors. The circuit is designed for circuit merit factor Q = 10. The proposed circuit implements three filter functions low pass, band pass and high pass simultaneously in single circuit. The filter circuit can be used for both narrow as well as for wide bandwidth. For various values of cut-off frequencies the behaviour of circuit is studied. The circuit works properly only for higher central frequencies, when f0 > 10 kHz.展开更多
文摘A novel three layers microstrip antenna element that has the advantages of wideband and high-gain is proposed. The eigenvalue equation and the frequency characteristic formulas of the input Voltage Stand Wave Ratio ( VSWR ) are obtained by using the spectral domain method and equivalent circuit method, respectively. With the aid of the numerical results, a C-band microstrip antenna element with bandwidth of 16% (VSWR【1.5) or 25% (VSWR【2) and gain of 10.2-11.3 dB is developed, which are much larger than the bandwidth of 5-6% and the gain of 6-7 dB of the common microstrip antenna element.
基金Supported by, the National Natural Science Foundation of China under Grant No 60537010.
文摘The electric and magnetic energy distributions in photonic crystals （PC） are calculated by using the plane wave expansion （PWE） method. Even though the total electric and magnetic energy in each unit cell of photonic crystals are equal to each other, the ratio of electric and magnetic energy densities varies depending on the local position. Based on Fermi＇s golden rule, the optical gain is analysed in the full quantum framework that takes the nonuniform energy density ratio into account. This nonuniform energy density ratio in photonic crystals, defined in an equal form as gain modification factor, leads to spatially inhomogeneous modification of optical gain. Results reported in the paper provide a new perspective for analysing gain characteristics, as well as the lasing properties, in photonic crystals.
基金Supported by the National Natural Science Foundation of China(No.61534003,61874024,61871116)
文摘The paper presents a fully integrated ultra-wide band(UWB)low noise amplifier(LNA)for 3-10 GHz applications.It employs self-biased resistive-feedback and current-reused technique to achieve wide input matching and low power characteristics.An improved biased architecture is adopted in the second stage to attain a better gain-compensation performance.The design is verified with TSMC standard 1 P6 M 0.18μm RF CMOS process.The measurement results show that the parasitic problem of the transistors at high frequencies is solved.A high and flat S21 of 9.7±1.5 dB and the lowest NF 3.5 dB are achieved in the desired frequency band.The power consumption is only 7.5 mA under 1.6 V supply.The proposed LNA achieves broadband flat gain,low noise,and high linearity performance simultaneously,allowing it to be used in 3-10 GHz UWB applications.
文摘This paper proposes third order tunable bandwidth active Switched-Capacitor filter. The circuit consists of only op-amps and switched capacitors. The circuit is designed for circuit merit factor Q = 10. The proposed circuit implements three filter functions low pass, band pass and high pass simultaneously in single circuit. The filter circuit can be used for both narrow as well as for wide bandwidth. For various values of cut-off frequencies the behaviour of circuit is studied. The circuit works properly only for higher central frequencies, when f0 > 10 kHz.
