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Help me fix my 1.5X charge pump circuit

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anyone can provide a detailed 1.5X charge-pump circuit? thanks

because my charge-pump with 1.5X is simulated, in phase 1: M0,M2 and M1 is turned on, the two cap' voltage drop is not equal to 1/2VDD. i can not find out the reason.
 

Re: about charge pump

One guess I have without seeing some sim results, what is the gate voltage on M2? The source of M2 ideally will see .5*VIN. So you need to ensure that your VGS is high enough to make M2 a low resistance switch. If you VGS is too low, and your sizing is too small the RDSon of M2 may be way too large thus your wrong voltage. For instance if you are driving M1 and M2 with the same gate voltage, M1 is going to have a much lower RDSon then M2. You may have to increase M2 or increase the VGS of M2. I think that is probably your problem.
 

Re: about charge pump

haff99 said:
One guess I have without seeing some sim results, what is the gate voltage on M2? The source of M2 ideally will see .5*VIN. So you need to ensure that your VGS is high enough to make M2 a low resistance switch. If you VGS is too low, and your sizing is too small the RDSon of M2 may be way too large thus your wrong voltage. For instance if you are driving M1 and M2 with the same gate voltage, M1 is going to have a much lower RDSon then M2. You may have to increase M2 or increase the VGS of M2. I think that is probably your problem.
Click to expand...
]


thank you , i will simulate it again.

Added after 1 hours 45 minutes:

haff99 said:
One guess I have without seeing some sim results, what is the gate voltage on M2? The source of M2 ideally will see .5*VIN. So you need to ensure that your VGS is high enough to make M2 a low resistance switch. If you VGS is too low, and your sizing is too small the RDSon of M2 may be way too large thus your wrong voltage. For instance if you are driving M1 and M2 with the same gate voltage, M1 is going to have a much lower RDSon then M2. You may have to increase M2 or increase the VGS of M2. I think that is probably your problem.
Click to expand...


but i use a pmos parallel with M2, the result is wrong. thanks!
 

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