what does this gate drive circuitry does

[Electro nS]

I have found this schematic online for a opensource H bridge DC servo drive with locked antiphase drive technique :



i want to know what is the role of the circuit at the gate of the mosfet , i usually use a 33ohm resistor with/or without anti parallel diode , but what does the capacitor (C16) does ? is it necessary ?

the other component which seems unnecessary is the diode placed across the mosfet , what does it do ? if you are working in 4 quadrant locked anti-phase , no need for freewheeling diode ??

the last thing is the RC snubber across the motor , is it necessary what does it do , does this provide extra protection , i am really interested in this ..
please explain

 

[barry]

This is not my field of expertise, but here goes: When TI_H goes high, the bulk of the current to charge the gate capacitance will initially flow through the 22 ohm and C16. As C16 charges, current will then flow only through the 200 ohm resistor. When T1_H goes low current will flow through the diode and the 22 ohm. So maybe what's going on here is they want the MOSFET to turn off faster than it turns on. That makes sense.

The diodes across the MOSFET are probably there because they are faster than the intrinsic diode. Why are there two in parallel? I have no idea.

The snubber is probably there to suppress voltage spikes, noise etc.