高频电子线路课后习题与答案 - 图文

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等效噪音带宽为：

? Bn=?0|H(j?)|2df2H0???0

?11df?df2?1?(?CRD)21?(2?fCR)D0?0?

1arctan(2?fCRD)2?CRD?11?4CRD4?100?10?12?561010??44.64MHz224 U2?2IqBH2n0n0?2?0.465?10?3?1.6?10?19?44.64?106?562?2083?(?V2)

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2－9 求图示的T型和П 型电阻网络的噪声系数。

题2－9图

解2-9

设两个电路的电源内阻为Rs

1. 解T型网络

（1）采用额定功率法

输入匹配功率PsmiEs2?，4Rs输出匹配功率Psmo2输出电阻为R0?(Rs?R1)R3?R2Rs?R1?R3??R3E??Rs?R1?R3s???4R02PR?R?R1?R3?噪音系数NF?smi?0??s?PsmoRs?R3?Word范文

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（2）采用开路电压法

（3）采用短路电流法

2Inio2Ino?4kTB2Unio??R3???4kTBRs，R?R?R13??s222Uno?4kTBR02UnoR?R?R1?R3?NF?2?0?s?UnioRs?R3?1R02

??RsR3?1????4kTB?RRRs?R2?R3?23R?R?s1??R2?R3??1?4kTBRs??RsR3??R(R?R?R)?R(R?R)133s1??2s2????2?R3Rs?R3???4kTBRs??4kTB2???R0?(Rs?R1?R3)???R3(Rs?R1)?(Rs?R1?R3)?R2?????R?R?Rs13????2InoR?R?R1?R3?NF?2?0?s?InioRs?R3?22Word范文

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2.解П型网络

?RsR1??R2?R3?R?R1?R1Rs?R2Rs?R1R2?R3?输出电阻为：R0??s?RsR1?(R2?R3)(Rs?R1)?RsR1?

?R2??R3??Rs?R1?

（1）采用额定功率法

得噪音系数为NF?Psmi

输出匹配功率Psmo输入匹配功率PsmiEs2?4Rs????RR31?Es??RsR1??Rs?R1?R?R23??Rs?R1???4R02Psmo?RsR1??R?R23?R0?R?Rs1????R??Rs1R??Rs?R13??22R?RR?(R2?R3)(Rs?R1)??0?s1?Rs?R1R3?1?R1Rs?R2Rs?R1R2????RsR0?R1?2Word范文