场效应管的分类:
![微信截图_20230616092327.png 微信截图_20230616092327.png](https://static.assets-stash.eet-china.com/forum/202306/16/092339w1x6xbq6o5e1dcc6.png)
1、 结型场效应管
根据导电载流子的不同,结型场效应管可分为N(电子型)沟道结型场效应管和P(空穴型)沟道结型场效应管。
1)结型场效应管的结构与类型
![微信截图_20230616093006.png 微信截图_20230616093006.png](https://static.assets-stash.eet-china.com/forum/202306/16/093015yr257555di5r3u5e.png)
![微信截图_20230616092747.png 微信截图_20230616092747.png](https://static.assets-stash.eet-china.com/forum/202306/16/092801mx54u6ud1rc5zue3.png)
2)结型场效应管的工作原理(以N沟道JFET为例)
![微信截图_20230616092904.png 微信截图_20230616092904.png](https://static.assets-stash.eet-china.com/forum/202306/16/092942c0wpr2b2vrve2rve.png)
![微信截图_20230616093050.png 微信截图_20230616093050.png](https://static.assets-stash.eet-china.com/forum/202306/16/093104d84q4byah8goaa7g.png)
综上分析可知:
![微信截图_20230616093315.png 微信截图_20230616093315.png](https://static.assets-stash.eet-china.com/forum/202306/16/093331otyg3y3qweiv2dlt.png)
2、 结型场效应管的伏安特性
1)输出特性
![微信截图_20230616093444.png 微信截图_20230616093444.png](https://static.assets-stash.eet-china.com/forum/202306/16/093455o631s53t5m5xv3z1.png)
![微信截图_20230616093531.png 微信截图_20230616093531.png](https://static.assets-stash.eet-china.com/forum/202306/16/093545tzfkz81g1oumwf81.png)
![微信截图_20230616093614.png 微信截图_20230616093614.png](https://static.assets-stash.eet-china.com/forum/202306/16/093626ozfilujievxkkuji.png)
2)转移特性
![微信截图_20230616093716.png 微信截图_20230616093716.png](https://static.assets-stash.eet-china.com/forum/202306/16/093727x2rzj4hdcgc0drsr.png)
3、 绝缘栅场效应管
结型场效应管在正常工作时PN结反偏,所以其输入电阻 较高,大于 ,但是反偏的PN结仍有微小的反向电流,所以当需要更高的输入电阻时,应采用绝缘栅场效应管。
![微信截图_20230616093836.png 微信截图_20230616093836.png](https://static.assets-stash.eet-china.com/forum/202306/16/093901qsrsc8ntgfjrsn88.png)
由于MOSFET制造工艺的成熟使它的体积可以做得很小,从而可以制造高密度的超大规模集成(VLSI)电路。而JFET放大电路应用较少。
4、 增强型MOS管
1)结构(以N沟道增强型MOS管为例)
![微信截图_20230616094043.png 微信截图_20230616094043.png](https://static.assets-stash.eet-china.com/forum/202306/16/094056y2lmuyf6565t8555.png)
2)工作原理
![微信截图_20230616094124.png 微信截图_20230616094124.png](https://static.assets-stash.eet-china.com/forum/202306/16/094241lvhhejmz2ovdkzht.png)
![微信截图_20230616094136.png 微信截图_20230616094136.png](https://static.assets-stash.eet-china.com/forum/202306/16/094256hqi39i5965jve5u9.png)
![微信截图_20230616094147.png 微信截图_20230616094147.png](https://static.assets-stash.eet-china.com/forum/202306/16/094308c9416nrrcc44q774.png)
![微信截图_20230616094200.png 微信截图_20230616094200.png](https://static.assets-stash.eet-china.com/forum/202306/16/094308b2iqnwi88ee67e26.png)
综上分析可知:
![微信截图_20230616094213.png 微信截图_20230616094213.png](https://static.assets-stash.eet-china.com/forum/202306/16/094308oqrddq18u54fa71q.png)
3)伏安特性
![微信截图_20230616094421.png 微信截图_20230616094421.png](https://static.assets-stash.eet-china.com/forum/202306/16/094437rs5ziiicc5psiszl.png)
![微信截图_20230616094458.png 微信截图_20230616094458.png](https://static.assets-stash.eet-china.com/forum/202306/16/094511l4aw6xkzeuydol6r.png)
5、耗尽型MOS管
二氧化硅绝缘层中掺有大量的正离子,已存在导电沟道。可以在正或负的栅源电压下工作,而且基本上无栅极电流。
![微信截图_20230616094615.png 微信截图_20230616094615.png](https://static.assets-stash.eet-china.com/forum/202306/16/094629zsqicyhvtt00s9w4.png)
6、 MOS管使用注意事项
1)由于MOS管的输入电阻极高,一般大于109Ω。在使用中,MOS管都应该避免栅极悬空。测试时所用仪器应保证接地良好,焊接时要将烙铁可靠接地。
2)MOS管在保存时需要将各极短路。
3)MOS管的源极与漏极在结构上是对称的,一般可将源极与漏极互换使用。如果MOS管内部已将衬底与源极短接,则源极与漏极不能互换。对于结型场效应管来说,漏极与源极是可以互换的。
7、场效应管的参数和小信号模型
1)场效应管的主要参数
![微信截图_20230616094835.png 微信截图_20230616094835.png](https://static.assets-stash.eet-china.com/forum/202306/16/094903pi449ti33yt14zyv.png)
2)场效应管的小信号模型
![微信截图_20230616094936.png 微信截图_20230616094936.png](https://static.assets-stash.eet-china.com/forum/202306/16/094953zd5wbpr1mhdb6blw.png)
3)场效应管与晶体管的比较
场效应管:源极(s)、栅极(g)、漏极(d)
晶体管:发射极(e)、基极(b)、集电极(c)
场效应管:截止区、恒流区、可变电阻区
晶体管:截止区、放大区、饱和区
主要区别:
![微信截图_20230616095126.png 微信截图_20230616095126.png](https://static.assets-stash.eet-china.com/forum/202306/16/095143zhfess97jt3t7tge.png)
8、场效应管放大电路(主要介绍基本共源极放大电路)
![微信截图_20230616095342.png 微信截图_20230616095342.png](https://static.assets-stash.eet-china.com/forum/202306/16/095452pcazpmgz5s90s5j0.png)
![微信截图_20230616095355.png 微信截图_20230616095355.png](https://static.assets-stash.eet-china.com/forum/202306/16/095452vnhmy75fhmy4mew7.png)
![微信截图_20230616095521.png 微信截图_20230616095521.png](https://static.assets-stash.eet-china.com/forum/202306/16/095531b7q7t7r2y863e7oq.png)
![微信截图_20230616095549.png 微信截图_20230616095549.png](https://static.assets-stash.eet-china.com/forum/202306/16/095602pq5p51kk651zqhq1.png)