Dear Team,

I was trying to study about bootstrapping in electronic circuits.

When I checked in Internet Wiki says it is a method to improve the input impedance of an amplifier.
In the power electronics context, it has another definition.(https://techweb.rohm.com/knowledge/dcdc/dcdc_sr/dcdc_sr01/829).
Here it has another meaning (https://m.eet.com/media/1152270/24127-45890.pdf).

Could you please clarify bootstrapping.

Regards
Hari

 

Bootstrapping comes from the analogy of lifting the feet higher from the ground, by pulling yourself from the straps in your boots.

It is an imperfect analogy, but you see the point: lifting a voltage from its ground.
This helps in the case of a SMPS output, to provide a proper gate drive to a high side Mosfet, when the source of that Mosfet may be lifted from ground hundreds of volts.

 

Bootstrapping comes from the analogy of lifting the feet higher from the ground, by pulling yourself from the straps in your boots.

It is an imperfect analogy, but you see the point: lifting a voltage from its ground.
This helps in the case of a SMPS output, to provide a proper gate drive to a high side Mosfet, when the source of that Mosfet may be lifted from ground hundreds of volts.

Hi Schmitt,

Thank you...

"lifting a voltage from its ground",may I know what this statement mean.We always need a ground in circuit rt.
Does it mean we are changing the reference ground?

Regards
Hari

 

Bootstrapping for power devices is often done by charging a capacitor to some desired voltage with one end of the cap at ground potential, and then lifting that capacitor ground connection to a higher potential (say the original charging voltage source).
The voltage at the top of the capacitor to ground will then be twice the charging voltage.
Remember, all voltages are relative between two points.

This bootstrapping is useful if you want a simple way to generate a voltage above the supply voltage, such as to drive a high-side N-MOSFET fully on, that requires a very small average current.

 

If you really want a challenge, look up boostrapping in a class AB audio amp. It took me the longest time to understand how that works. (It really is the same thing as the other examples.)

Bob

 

If you really want a challenge, look up boostrapping in a class AB audio amp. It took me the longest time to understand how that works. (It really is the same thing as the other examples.)

Bob

Hi Bob,

Thank you
Could you please send me the circuit.

Regards
Hari