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
Transistors are nonlinear devices, which can produce nonlinear distortion in amplifier while amplifying signals. For weak nonlinear distortion, the expressions of total harmonic distortion (THD), the second order in...Transistors are nonlinear devices, which can produce nonlinear distortion in amplifier while amplifying signals. For weak nonlinear distortion, the expressions of total harmonic distortion (THD), the second order intermodulation distortion(IM2 ), the third order intermodulation distortion(IM 3) and intercept point(IP 3) are deduced. With the aid of software Multisim, we simulate transistor common emitter amplifier, transistor common emitter amplifier with resistor in emitter, differential amplifier and differential amplifier with resistor between emitters. The simulational results and theoretical analyses are almost the same.展开更多
This paper presents an analog predistortion circuit for RF optical fiber links. The circuit consists of two source-coupled differential transconductance amplifiers which could provide linear and nonlinear transfer cha...This paper presents an analog predistortion circuit for RF optical fiber links. The circuit consists of two source-coupled differential transconductance amplifiers which could provide linear and nonlinear transfer characteristics by adjusting the bias voltage and the transistor sizes. The circuit was designed and realized in a standard 0,18-μm CMOS technology of SMIC. The chip occupies 0.48 × 0.24 mm^2. The DC supply is 3.3 V. Using this circuit, the third-order intermodulation distortion （IMD） suppression of a directly modulated RF optical fiber link can be improved by 9-16 dBc at relatively low cost.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
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Transistors are nonlinear devices, which can produce nonlinear distortion in amplifier while amplifying signals. For weak nonlinear distortion, the expressions of total harmonic distortion (THD), the second order intermodulation distortion(IM2 ), the third order intermodulation distortion(IM 3) and intercept point(IP 3) are deduced. With the aid of software Multisim, we simulate transistor common emitter amplifier, transistor common emitter amplifier with resistor in emitter, differential amplifier and differential amplifier with resistor between emitters. The simulational results and theoretical analyses are almost the same.
基金Project supported by the High-Tech-Program of China (No.2007AA01Z2a5)
文摘This paper presents an analog predistortion circuit for RF optical fiber links. The circuit consists of two source-coupled differential transconductance amplifiers which could provide linear and nonlinear transfer characteristics by adjusting the bias voltage and the transistor sizes. The circuit was designed and realized in a standard 0,18-μm CMOS technology of SMIC. The chip occupies 0.48 × 0.24 mm^2. The DC supply is 3.3 V. Using this circuit, the third-order intermodulation distortion （IMD） suppression of a directly modulated RF optical fiber link can be improved by 9-16 dBc at relatively low cost.
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.
