求助关于class AB输出级电流控制电路的问题

zzyhpu · 发表于 2011-4-4 23:28:25

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本帖最后由 zzyhpu 于 2011-4-4 23:34 编辑

我在一篇文章：Low-Power Low-Voltage Chopped Amplifier with a New Class AB Output

中看到一个AB类输出级电流控制电路，说是为了“驱使M35，M36周期性脱离高阻节点，且运用了反馈控制”，不知道这个电路怎么分析，不知道M32，M34和Imin的作用是什么，还请高人指点。这篇文章在没法发链接，google上可以搜到，sectionⅣ。

esbwong · 发表于 2011-4-5 00:05:30

Vgs_M32 + Vgs_M34 = Ebiasn due to feedback loop

Imin mainly to shift up lowest drain currents in M35/M36.

sdmout · 发表于 2011-4-5 07:30:04

I think this is a new type of "minimum current selector" formed by M32-34.
M32 and M33 are the current sensors that monitoring the output current of M35 and M36, and the minimum current among the two decide the gate voltage of M15, which should be equal to Ebiasn.

You may search "translinear circuit", and "minimum current selector" to get more detailed analysis.

zzyhpu · 发表于 2011-4-5 23:35:18

谢谢各位解惑！我看过的文章中好像有“maximum current selector”，不知是不是3楼所提的第二种类型？

zzyhpu · 发表于 2011-4-5 23:43:29

Imin mainly to shift up lowest drain currents in M35/M36.

为什么要用Imin上调M35/M36的最低漏电流呢？

sdmout · 发表于 2011-4-6 12:04:45

Minimum current selector controls the output transistors M35/36, that none of them would be completely turned off, i.e there is always a residue current.

zzyhpu · 发表于 2011-4-6 15:11:22

关于这篇文章，在sectionⅣ我还有一句不明白：“若晶体管M34，M32工作于弱反型区且正向饱和（Vds>>UT），则可以得到条件（3）”。
为什么在“弱反型又正向饱和”呢？条件（3）怎么得到的？

sdmout · 发表于 2011-4-6 17:16:12

I don't have that paper. But it could be translinear loop related. M32,34 and M14,15 form a translinear loop, that control the class ab behavior. Weak inversion may help the translinear relations. You may need to read something about CMOS translinear circuits.

I'll find this paper, and get back to you later.

jarviszh · 发表于 2011-5-6 14:01:47

给大家付上这篇文章

floatice · 发表于 2011-8-14 09:15:13

Good goood

[求助] 求助关于class AB输出级电流控制电路的问题

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