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Introduction to IMPATT Diodes
IMPact Avalanche Transit Time (IMPATT) Proposed by Read in 1958† Deloach† † reviewed the theory based on experimental results Generates frequency-dependent negative resistance Operates in avalanche breakdown Possible IMPATT structures p+ i n+ p+ n n+ p+ n i n+ 1 2 3 † W. T. Read, “A Proposed High-Frequency Negative-Resistance Diode,” Bell Syst. Tech. J., (1958). † † B. C. DeLoach, “ The IMPATT Story,” IEEE Trans. Electron Devices, v.23 no.7, July 1976.
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Basic IMPATT Operation
+ - Drift Region p+ n n+ n n 2 Avalanche Region AC Voltage Electric field profile Distance along the diode Ec Injected External AC Current
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RF Measurements (Coplanar Waveguide)
GND Signal n+ p+ GND n-well IMPATT Diode IMPATT diodes have been: Monolithically integrated in coplanar waveguides Characterized by S-parameter measurements from 40MHz to 110GHz
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负阻振荡器：利用负阻器件抵消回路中的正阻损耗，产生自激振荡的振荡器。由于负阻器件与回路仅有两端连接，故负阻振荡器又称为“二端振荡器”。
负阻器件的基本特性 一、负阻的概念 常见的电阻，不论线性电阻还是非线性电阻，都属于正电阻。其特征是流过电阻电流越大，其电阻两端的电压降也越大，消耗功率也越大，如下图所示。三者的关系为 这里 3.7.1
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6.4 共振隧穿二极管
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共振隧穿的概念 1.能级是量子化的,有一量子阱,不同于一般势垒;
2.入射电子能级E=E1或E2或E3…,有很大的隧穿系数(透射率),称为共振隧穿; 3.单势垒透射率也许不到1%,但对于对称双势垒,其透射率可达100%.
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