After trying to ask multiple times my professor what he meant with this I still don't get it.
Basically I have an inverting amplifier with a specified gain-bandwidth product of 0.6 MHz. Now as I understand we have that the gain-bandwidth product is calculated multiplying the closed-loop gain with the bandwidth. Now the closed-loop gain is calculated with the ratio of resistances and it corresponds to 20 in my circuit. Therefore the bandwidth is 30 KHz. Now my professor tells me that the closed-loop gain must be in decibels in that formula and therefore it should be about 23 kHz. I don't get why the closed-loop gain needs to be in decibels in this formula, can someone please explain me?