Building a Low-Cost White-Nois
abstract: a design idea for a white-noise generator is realized and revised. two low-noise amplifiers (lnas) in cascade amplify the noise produced by a reverse-biased zener diode operating in junction-breakdown mode, producing white noise with a bandwidth of several hundred megahertz. the test results show that a fairly wideband white noise can be generated using several inexpensive components.
white noise, which is defined as noise with constant power spectrum, is useful for measuring and testing wide-band communication circuits. commercially available white noise generators are usually very expensive. the design idea presented in this article is an inexpensive method that produces white noise up to several hundred mhz.
this white noise generator is based on the avalanche noise generated by a zener breakdown phenomenon. it is created when a pn junction is operated in the reverse breakdown mode. the avalanche noise is very similar to shot noise, but much more intense and has a flat frequency spectrum (white). the magnitude of the noise is difficult to predict due to its dependence on the materials.
basically the circuit has 2 portions: a zener diode, and max2611 low noise amplifiers (lna). the diode is reverse-biased and noise output is taken from the anode. the max2611 is a wide-band low-noise-amplifier with 19db gain operating from dc to 1ghz.
summary of test resultsthe white noise generator circuit is realized with 2 boards, one for the zener diode, one for the max2611 lna. the output trace from the anode of the zener to the input of the lna is designed to be 50ω. the output of the lna is measured by a rhode & schwarz spectrum analyzer. for practical purpose, noise power of -60dbm or above is desired within the frequency band of interest.
after several experiments, i obtained the following results: the noise output power is mostly decided by the diode's breakdown voltage. i have used zener diodes with breakdown voltage of 4v(1n749), 5.1v(1n751), 5.6v(1n752), 7.5v(1n755), and up to 12v(1n759). 12v zener generated noise power is at least 15~20db higher than that generated by 5v zener. even with 12v zener, 20db gain from the lna is not enough to produce noise power higher than -60dbm. we need at least two lnas in cascade (38~40db gain). the output noise power is almost independent of the source current. with the potentiometer, the current into the diode can vary from 0ma to 100ma. within this source current range, the noise power varies pretty randomly within ±1db. it seems in zener diode breakdown phenomena, the avalanche noise dominates over other noise source, such as shot noise (which is proportional to current), flicker noise and thermal noise. the frequency/power spectrum of the output noise is not perfectly flat over a wide frequency range. as shown in test result figure 2, from 1mhz to 100mhz, noise power drops almost 10db. this could be because of higher on-board attenuation for higher frequency components. 2 lnas were used in cascade for the white noise generator, which produced 38~40db gain.the circuit is shown in figure 1, and the test result is shown in figure 2. in figure 2, the bottom curve is the instrument noise floor (measured when everything is off). the second curve from bottom is the noise output from the lna when the diode is off. the top 2 curves are noise output spectrum at 10ma and 60ma diode current respectively.
figure 1. white-noise generator circuit.
figure 2. white-noise generator output spectrum.
conclusionin this article, a design idea of a white noise generator is realized the test result shows a pretty wide-band white noise generated with several inexpensive components.
a similar version of this article appeared in the september-october 2004 issue of electronica magazine.
用单片机设计制作的开水器智能检测控制电路
二维码与物联网产业以更好的姿态和方式进行配合式发展
介绍 Nginx的基本概念,性能,SSL 安装
三种先进晶圆清洁工艺介绍
我国工业互联网发展受到了哪些阻力?
Building a Low-Cost White-Nois
蓝牙5.0对比4.2的主要优势
FPGA设计效能提高方法
气压可视泄漏点检测仪工作具体流程
C2000 MCU flash报错的解决方案
先锋影像旗舰vivo S12系列正式发布：全面提升、全面出色
超声波传感器 MB7389如何在腐蚀性环境中提升耐酸耐腐蚀性能的？
CAN FD芯片保护TVS二极管选型
桥式整流器型号大全_桥式整流器怎么测好坏
华为推出乾坤安全云服务解决方案 确保端到端安全和可信
韦尔品牌的线性稳压器WL2803E
LOTO示波器如何测试阻抗的频响曲线
terawins T102
TCL宣布出售金能电池 聚焦主导产业变革计划
什么叫发动机启停技术_发动机启停技术有用吗
white noise, which is defined as noise with constant power spectrum, is useful for measuring and testing wide-band communication circuits. commercially available white noise generators are usually very expensive. the design idea presented in this article is an inexpensive method that produces white noise up to several hundred mhz.
this white noise generator is based on the avalanche noise generated by a zener breakdown phenomenon. it is created when a pn junction is operated in the reverse breakdown mode. the avalanche noise is very similar to shot noise, but much more intense and has a flat frequency spectrum (white). the magnitude of the noise is difficult to predict due to its dependence on the materials.
basically the circuit has 2 portions: a zener diode, and max2611 low noise amplifiers (lna). the diode is reverse-biased and noise output is taken from the anode. the max2611 is a wide-band low-noise-amplifier with 19db gain operating from dc to 1ghz.
summary of test resultsthe white noise generator circuit is realized with 2 boards, one for the zener diode, one for the max2611 lna. the output trace from the anode of the zener to the input of the lna is designed to be 50ω. the output of the lna is measured by a rhode & schwarz spectrum analyzer. for practical purpose, noise power of -60dbm or above is desired within the frequency band of interest.
after several experiments, i obtained the following results: the noise output power is mostly decided by the diode's breakdown voltage. i have used zener diodes with breakdown voltage of 4v(1n749), 5.1v(1n751), 5.6v(1n752), 7.5v(1n755), and up to 12v(1n759). 12v zener generated noise power is at least 15~20db higher than that generated by 5v zener. even with 12v zener, 20db gain from the lna is not enough to produce noise power higher than -60dbm. we need at least two lnas in cascade (38~40db gain). the output noise power is almost independent of the source current. with the potentiometer, the current into the diode can vary from 0ma to 100ma. within this source current range, the noise power varies pretty randomly within ±1db. it seems in zener diode breakdown phenomena, the avalanche noise dominates over other noise source, such as shot noise (which is proportional to current), flicker noise and thermal noise. the frequency/power spectrum of the output noise is not perfectly flat over a wide frequency range. as shown in test result figure 2, from 1mhz to 100mhz, noise power drops almost 10db. this could be because of higher on-board attenuation for higher frequency components. 2 lnas were used in cascade for the white noise generator, which produced 38~40db gain.the circuit is shown in figure 1, and the test result is shown in figure 2. in figure 2, the bottom curve is the instrument noise floor (measured when everything is off). the second curve from bottom is the noise output from the lna when the diode is off. the top 2 curves are noise output spectrum at 10ma and 60ma diode current respectively.
figure 1. white-noise generator circuit.
figure 2. white-noise generator output spectrum.
conclusionin this article, a design idea of a white noise generator is realized the test result shows a pretty wide-band white noise generated with several inexpensive components.
a similar version of this article appeared in the september-october 2004 issue of electronica magazine.
用单片机设计制作的开水器智能检测控制电路
二维码与物联网产业以更好的姿态和方式进行配合式发展
介绍 Nginx的基本概念,性能,SSL 安装
三种先进晶圆清洁工艺介绍
我国工业互联网发展受到了哪些阻力?
Building a Low-Cost White-Nois
蓝牙5.0对比4.2的主要优势
FPGA设计效能提高方法
气压可视泄漏点检测仪工作具体流程
C2000 MCU flash报错的解决方案
先锋影像旗舰vivo S12系列正式发布：全面提升、全面出色
超声波传感器 MB7389如何在腐蚀性环境中提升耐酸耐腐蚀性能的？
CAN FD芯片保护TVS二极管选型
桥式整流器型号大全_桥式整流器怎么测好坏
华为推出乾坤安全云服务解决方案 确保端到端安全和可信
韦尔品牌的线性稳压器WL2803E
LOTO示波器如何测试阻抗的频响曲线
terawins T102
TCL宣布出售金能电池 聚焦主导产业变革计划
什么叫发动机启停技术_发动机启停技术有用吗