How can an increase of biasing currents increase the bandwidth of a negative feedback amplifier?
Please explain in easy terms since I am pretty new to electronics. Thanks.
In general - increased bias currents mean that lower resistances are generally used. For example, a load resistor might be 200 ohms instead of 20kohms. Why does this affect BW? In a word - parasitics. Every component has some (unwanted) parasitics like lead inductance, shunt capacitance. These parasitics are generally related to the physical construction of the device, not the value. So, a 200 ohm resistor will have the same parasitic inductance and capacitance as a 20kohm resistor. At a given frequency, the parasitic elements will alter the value of a 20k resistor much more than a 200 ohm resistor - thus making the 200 ohm resistor usable at higher frequencies.
In general - increased bias currents mean that lower resistances are generally used. For example, a load resistor might be 200 ohms instead of 20kohms. Why does this affect BW? In a word - parasitics.
It could help with parasitic capacitances, but not inductances. Higher current could charge/discharge capacitances faster. As you say, for smaller resistances, capacitance will have a smaller effect but inductance will have a larger effect.
For bipolars, higher current would give higher transconductance, which might help with gain BW product
The question is too vague.