5V单电源供电的低噪声宽带放大器

Low noise wideband amplifier with 5V single power supply

以单片机MSP430F449为控制核心,设计了一个5 V单电源供电的低噪声宽带放大器。采用单位增益稳定低噪声运放OPA820作为前级放大,高速运放THS3091作为末级放大,其中利用DC-DC变换器TPS61087将5 V电压转化为18 V从而为末级放大电路供电。此外,系统还采用12位高速A/D转换器ADS803实现了测量并数字显示放大器输出电压峰峰值的功能,测量误差小于5%。本系统最高电压增益达到43 dB,上限及下限截止频率达到15 MHz和20 Hz,在50Ω负载上,最大不失真输出电压峰峰值为4.2 V。系统的输出噪声小于200 mV。

Using microcontroller MSP430F449 as the operation core,a low noise wideband amplifier provided with 5V single power supply is designed. The preamplifier is achieved by using OPA820,which is a unity-gain stable,low-noise amplifier. The last amplifier is achieved by using high-speed amplifier THS3091. A DC to DC converter T1~61087 is used to provide power supply for the last amplifier module,which can switch 5V voltage to 18V. Besides,the system can measure and display the peak-peak value of the output voltage by using the 12-bit high-speed ADC ADSS03,and the measurement error is lower than 5%. The highest gain of the system can reach 43dB,the upper and lower cut-off frequency can reach 15MHz and 20Hz,and the biggest undistorted output voltage is 4.2V with 50Ω load. The output noise of the system is lower than 200mV.