Return to Answer

Bootstrapping, in both usages, means the arrangement of TWO nodes of the circuit that are coupled in such a way that one (controlled) node will closely follow the (controller) node.

• if a emitter follower uses the emitter output voltage to drive the collector voltage, then the Cob is removed from the Cin computation. This requires a large resistor in the collector to VDD, otherwise the emitter would not be able to move the collector voltage. A bipolar with Cob of 5pF, and a bootstrap cap from emitter to collector of only 5pF, will not optimally minimize the input capacitance; notice this is positive feedback, and some configurations of this are called "oscillators".

• another use is in high_side switching, using Nchannel FETs; a special capacitor Cboot must be charged up, and then charge is stolen from Cboot to control the Cgate of the FET during each switching cycle.

• also the standard opamp non_inverting gain configuration is "bootstrapping" in that differential input capacitance is largely ignorable, as is differential input current. Thus the primary Rin (aka Zin) becomes the common_mode behavior. Note the Miller Multiplication (by non_cascoded input diffpairs) remains a problem; and during slewing, there is no Miller Multiplication, making the Cin become highly NON_LINEAR and upsetting the settling behavior.

Please read the comments by "jonk" and examine his links.

Bootstrapping, in both usages, means the arrangement of TWO nodes of the circuit that are coupled in such a way that one (controlled) node will closely follow the (controller) node.

• If an emitter-follower uses the emitter output voltage to drive the collector voltage, then the Cob is removed from the Cin computation. This requires a large resistor in the collector to VDD, otherwise the emitter would not be able to move the collector voltage. A bipolar with Cob of 5pF, and a bootstrap cap from emitter to collector of only 5pF, will not optimally minimize the input capacitance; notice this is positive feedback, and some configurations of this are called "oscillators".

• Another use is in high_side switching, using N-Channel FETs; a special capacitor Cboot must be charged up, and then charge is stolen from Cboot to control the Cgate of the FET during each switching cycle.

• Also, the standard OpAmp non_inverting gain configuration is "bootstrapping" in that differential input capacitance is largely ignorable, as is differential input current. Thus the primary Rin (aka Zin) becomes the common_mode behavior. Note the Miller Multiplication (by non_cascoded input diffpairs) remains a problem; and during slewing, there is no Miller Multiplication, making the Cin become highly NON_LINEAR and upsetting the settling behavior.

Please read the comments by "jonk" and examine his links.

Bootstrapping, in both usages, means the arrangement of TWO nodes of the circuit that are coupled in such a way that one (controlled) node will closely follow the (controller) node.

• if a emitter follower uses the emitter output voltage to drive the collector voltage, then the Cob is removed from the Cin computation. This requires a large resistor in the collector to VDD, otherwise the emitter would not be able to move the collector voltage. A bipolar with Cob of 5pF, and a bootstrap cap from emitter to collector of only 5pF, will not optimally minimize the input capacitance; notice this is positive feedback, and some configurations of this are called "oscillators".

• another use is in high_side switching, using Nchannel FETs; a special capacitor Cboot must be charged up, and then charge is stolen from Cboot to control the Cgate of the FET during each switching cycle.

Please read the comments by "jonk" and examine his links.

Bootstrapping, in both usages, means the arrangement of TWO nodes of the circuit that are coupled in such a way that one (controlled) node will closely follow the (controller) node.

• if a emitter follower uses the emitter output voltage to drive the collector voltage, then the Cob is removed from the Cin computation. This requires a large resistor in the collector to VDD, otherwise the emitter would not be able to move the collector voltage. A bipolar with Cob of 5pF, and a bootstrap cap from emitter to collector of only 5pF, will not optimally minimize the input capacitance; notice this is positive feedback, and some configurations of this are called "oscillators".

• another use is in high_side switching, using Nchannel FETs; a special capacitor Cboot must be charged up, and then charge is stolen from Cboot to control the Cgate of the FET during each switching cycle.

• also the standard opamp non_inverting gain configuration is "bootstrapping" in that differential input capacitance is largely ignorable, as is differential input current. Thus the primary Rin (aka Zin) becomes the common_mode behavior. Note the Miller Multiplication (by non_cascoded input diffpairs) remains a problem; and during slewing, there is no Miller Multiplication, making the Cin become highly NON_LINEAR and upsetting the settling behavior.

Please read the comments by "jonk" and examine his links.

Bootstrapping, in both usages, means the arrangement of TWO ndoes of the circuit that are coupled in such a way that one (controlled) closely follows the (controller) node.

• if a emitter follower uses the emitter output voltage to drive the collector voltage, then the Cob is removed from the Cin computation. This requires a large resistor in the collector to VDD, otherwise the emitter would not be able to move the collector voltage

• another use is in high_side switching, using Nchannel FETs; a special capacitor Cboot must be charged up, and then charge is stolen from Cboot to control the Cgate of the FET during each switching cycle.

Bootstrapping, in both usages, means the arrangement of TWO nodes of the circuit that are coupled in such a way that one (controlled) node will closely follow the (controller) node.

• if a emitter follower uses the emitter output voltage to drive the collector voltage, then the Cob is removed from the Cin computation. This requires a large resistor in the collector to VDD, otherwise the emitter would not be able to move the collector voltage. A bipolar with Cob of 5pF, and a bootstrap cap from emitter to collector of only 5pF, will not optimally minimize the input capacitance; notice this is positive feedback, and some configurations of this are called "oscillators".

• another use is in high_side switching, using Nchannel FETs; a special capacitor Cboot must be charged up, and then charge is stolen from Cboot to control the Cgate of the FET during each switching cycle.

Please read the comments by "jonk" and examine his links.