Bootstrapping (electronics)

[1] In the domain of MOSFET circuits, bootstrapping is commonly used to mean pulling up the operating point of a transistor above the power supply rail.

[4] In the sense used in this paragraph, bootstrapping an operational amplifier means "using a signal to drive the reference point of the op-amp's power supplies".

[5] A more sophisticated use of this rail bootstrapping technique is to alter the non-linear C/V characteristic of the inputs of a JFET op-amp in order to decrease its distortion.

One popular case where this is done deliberately is the Miller compensation technique for providing a low-frequency pole inside an integrated circuit.

However, eventually the capacitor will lose its charge due to parasitic gate current and non-ideal (i.e. finite) internal resistance, so this scheme is only used where there is a steady pulse present.

Emitter followers can provide rail-to-rail output in this way, which is a common technique in class AB audio amplifiers.

Within an integrated circuit a bootstrap method is used to allow internal address and clock distribution lines to have an increased voltage swing.

The bootstrap circuit uses a coupling capacitor, formed from the gate/source capacitance of a transistor, to drive a signal line to slightly greater than the supply voltage.