Thirty amps seems like a lot but it isn't. You want the transition to be as short as possible to reduce heating in the MOSFET. Ideally, you want the transition to take zero time.
Well... not really. Gamma ray bursts from a gate driver would be rather extreme.
Even ignoring the absurd case (
literally zero
), there are very good reasons not to have transitions of, say, single nanoseconds. Even besides device characteristics (you'll be somewhat hard pressed to find a gate driver, in stock, with less than 20ns risetime, or a transistor that can be pushed so fast besides) and EMI concerns, the physical layout of the circuit itself may prohibit such short time scales.
This is simply because, as current flow rises, part size rises, the number and size of bypass capacitors rises, and trace widths and lengths rise. The dimension scale rises, and stray inductance rises proportionally.
The solution is, dividing the circuit into smaller pieces, which can handle it. This is part of the reason why PC motherboards have so damned many phases supplying Vcore.
This is also why FM radio transmitters use many small modules with power combiners, rather than a single monolithic device. The only thing that can handle that much power, in a single unit, at that frequency, is a vacuum tube! But those are inefficient and less reliable, and therefore less cost-effective today.
And why large industrial modules are only available in IGBT flavor -- why bother with MOSFETs at all, when the part is so large that you can't possibly harness the speed advantage? (Efficiency is a bonus, and the historical priority -- but no longer true with newer developments in SJ Si, SiC and GaN FETs. Hmm, it'll be interesting to see if anyone tries introducing a power switching module that's GaN based, with integrated bypass caps and gate drivers.)
You really don't want any unnecessary resistance in the gate circuit in an attempt to slow down switching. This leads to heating in the MOSFET because it doesn't fully transition fast enough. If you need to deal with punch-through, do it ahead of the driver/MOSFET circuitry. Once you gate the driver, it's time to go! No messing around!
It is easy to find situations where increasing gate resistance
reduces switching loss.
Incidentally, it's also easy to find situations where increasing stray gate drive inductance
reduces rise time. (That's just good old fashioned series peaking.)
Tim