I'm looking at some transistor radio circuits and the book I'm following makes the following statement with regard to AC gain: "By raising the DC voltage at the collector, the internal collector-base capacitances of the transistor are reduced".
Here's a circuit to help understand what's going on:
Here the author has killed the DC gain by placing an inductor in parallel with R2 whilst leaving the AC gain intact: collector reactance (L1||R2) / emitter reactance (C3||R3).
I have a reasonable grasp of the effect of Miller Capacitance on an inverting amplifier, where the inverted output acts negatively on the input. What I don't understand is why increasing the collector voltage acts to reduce collector-base capacitance.
Does the increase in current flowing through the collector-emitter junction have anything to do with it?