TIDA-010030: about the Q22 function and the wake up circuit

Part Number: TIDA-010030
Other Parts Discussed in Thread: BQ76200

I want to know the Q22 function.

 When a right charge is attached, Q15 will be
turned on and pull TS1 high, and because of C20 and C18, Q15 will be turned off, generating a wake up
signal on TS1 pin.

about the because C20 and C18, can you explain?