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发表于 2015-10-13 17:08:34
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CAP电压是在VP(PMOS栅极电压),VN(NMOS栅极电压)之间摆动的锯齿波。
1. CAP>VP, RST=1, SET=0 => QB=1, starting discharge;
2. VN<CAP<VP, RST=0, SET=0 => QB stays 1, continuing discharge;
3. CAP<VN, RST=0, SET=1 => QB=0, starting charge;
4. VN<CAP<VP, RST=0, SET=0 => QB stays 0, continuing charge;
......
Period = 2(VP-VN)C/I,
这玩意儿PVT variation太大了吧,而且还要保证VP>VN.
如果偏置变成diode connected PMOS - resistor - diode connected NMOS,倒是可以做成一个比较准的RC relaxation oscilaltor
Period = 2RC. |
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