Questions re the circuit - cross coupled mosfets, long-tail pair

[shemo]

1)what's the purpose of MP19?
2) Why the loads MP11 and MP12 are cross coupled?
3)what's the purpose of MP15 and MP16?

thanks

 

[erikl]

1) to switch off the whole circuit to "zero current" consumption when H=low, by preloading node Z to high. H=≈ "latch enable" (pos. logic)
2) positive feedback to increase gain
3) usually called "hysteresis transistors". Here they are used to preload the output nodes to "high" when H="low", to change the hysteresis during its transition from "low" to "high" and provide the latching at H="high".

I'd call the circuit "latched comparator".