Attiny13A Qi wireless power receiver. 
PB4 to be connected to mosfet gate for modulation.
Power the ATtiny13A from a regulated 5v with a parallel capacitor not greater than 10uF. 
Power the regulator input from the rectified output of the receiver coil circuitry according to the schematic.
PB3 to be connected to rectified DC voltage via 4.7/47k divider).

Schematic: Please visit
http://blog.vinu.co.in/2019/04/qi-wireless-power-receiver-from-scratch.html