I am designing a charge pump(voltage doubler , volatge trippler ) in a low voltage technology.My problem is the power effeciency of the charge pump.I am not ablle to achieve power efficiency greater than 75%.
Technlogy parameters
voltage=1.2v
|vt| (nmos, pmos)=0.40
Can any one please suggest me the concept behind it and help me in achieving power efficiency around 90%.references regarding this is most welcome.
ther is a trade-off between transistor size and efficiency:
larger transistors need more charge at their gate, thus there is a optimum value for the size.
BTW, I think 75% efficiency is not so bad specially if it is low power!
For traditional structure,you can try use native transistor(vt=0) to improve power efficiency suppose vout and vdd is fixed.
Also you can refer to "Charge Sharing Concept and New Clocking Scheme for Power Efficiency and Electromagnetic Emission Improvement of Boosted Charge Pump", IEEE JSSC,Vol 35,No.5,May 2000
you can improve the gate voltage(such as bootstrap) of switch mos fet for high effciency.
btw, the effciency is a function of output current. If you added the output current, the effciency will increase.
what is meaning of " high gate voltage which beyond your power range will increase the efficiency"
Please give me some explanations or some papers?
thank you
I want to design a switched mode power supply.I want to reduce the mosfet driver consupmtion.
The lower threshold voltage means the higher speed.
How the low threshold voltage can reduce the power consumption?
For my case, the vt=0.4V ,so, it has necessary to reduce the vt use body effect or not?
"high gate voltage" will reduce mosfet RDS_on,so it can increase efficiency.
Low gate cap(miller cap) can reduce gate drive current,But for same mosfet,Higher frequency will reduce efficiency.
wait, switchmode power supply is different from the integrated charge pump that opamp is talking about.
for smps, you usually connect a boost capacitor to the LX line, and then have a shottky diode to vin. as LX falls, the boost diode is filled to VIN. When LX Rises, the boost cap follows up to 2*VIN. No other pumping is needed in SMPS.
Now on to opamp's question - opamp, I have a bunch of references on charge pumps. Maybe too many to post here - can you tell me the topology you use? Then I think I can help you more.