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CMOS DC booster - Start up circuit

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johnnysp

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Hello everybody,

I'm new in this forum and i have some questions about a dc-dc booster creating for my diploma thesis.
dc_booster.JPG
I have the above circuit. Mos-switch is designed in 0.13um. I want to have an output voltage to 1V coming from an input one of 50mV - 80mV. The problem I am facing is that i can achieve having this output voltage only when the width of mos-switch is some cm. However, in this case, the power consumption of mos-switch is nearly 100% of vdc's power.
Could you help me about that? How can I have both output voltage and least power consumption of mos?
 

You are asking for up to 20X increase. This means the duty cycle needs to be very high, on the order of 97 or 98% (according to my simulation). During that part of the cycle, current goes through the switching device (mosfet).

Hence only 2 or 3 percent of each cycle goes to the output stage.

It is normal operation in a boost converter, if you wish to get 20X increase.
 

I change duty cycle but power consumption in MOS is still to 100%. The only way i could decrease consumprion was by changing width of MOS to micrometers. However, in this way voltage boosting is nowhere. Any idea of how I could reach both targets?
 

Change your topology; use a boost circuit which permits the use of a transformer—one with perhaps a 10:1 turns ratio.
 

What do you mean saying "use a transformer"?

Using, for example, model IRF034 and Vin=50m, L=22u, C=10u, RL=100k, the result of Vout=1.4V which is pretty good. However, power consumption in MOS switch is 100% of Vin's power. My Vpulse generator has Period=10m, PW=7.5m and V=1V. What changes could I make in these parameters?
 
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Come to think of it, if your power supply is .05V, then it is not able to turn on semiconductors, even if it has unlimited amperes available.

A flyback converter will perform with better efficiency. It uses a transformer which contains a primary and secondary. This is only theoretical talk of course. You will still need 1V or so, to turn on a switching device for a flyback.
 

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