# Equatios for DC-DC converter..Boost Converter...

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#### bharatsmile2007

##### Full Member level 3 hi all,

can anyone provide me the equations for Boost Converter?The equations for finding out L,C?

Thanks a lot....

#### erikl

##### Super Moderator
Staff member Wiki provides the equations.
And - if you don't mind it's in German ;-) .

### bharatsmile2007

Points: 2

#### bharatsmile2007

##### Full Member level 3 Thanks for the info..

can you tell me,how to do ac analysis for boost converter(pls find the attachement)..?

I need to find the gain and phase margin for the same...When I am giving ac=1(magnitude) the gain is 0dB, but when I give ac=10m 0r any other value I see a gain.

Is it that i need to give only ac=1 and not any other value for doing ac simulation?

Would you pls clarify my doubt, why only ac=1 and not any other value?

#### erikl

##### Super Moderator
Staff member Re: Ac analysis

bharatsmile2007 said:
When I am giving ac=1(magnitude) the gain is 0dB, but when I give ac=10m 0r any other value I see a gain.

Is it that i need to give only ac=1 and not any other value for doing ac simulation?

Would you pls clarify my doubt, why only ac=1 and not any other value?
All frequency-domain analyses (AC, XF, SP, TDR, noise) use a linearized circuit around a DC operating point (which is calculated first). So it doesn't matter, which magnitude of input voltage (or current) you inject: it can be 1mV, 1V or even 1kV (overmodulation or clipping effects don't exist with a linearized circuit model). The gain is always output_voltage/input_voltage, and it doesn't vary at a linearized circuit. Because it is rather convenient to divide by "1", usually this input magnitude unit is used. Hence the gain is equivalent to the numerical value of the output voltage in such case.

If you think you got a different result when injecting a different input magnitude, you most probably forgot to divide output_voltage/input_voltage.

Points: 2