Hello,
I would like to drive a synchronous two mosfets which work as buck converter. The pwm source is a PIC mcu. How can I drive properly without a IC.
You don't say which PIC you are using, but the PIC16F684 can drive FETs in a half bridge configuration. You will still need to level shift the signal for Q1. The hard part is going to be adjusting the dead time between FETs. The 16F684 has a adjustable dead timer built in.
The simplest way without an IC is to use a transformer. I'd just use an IC designed for this application. It'll save you some headaches.
If Q1 was a P channel device, you could possibly use a capacitor, resistor and diode clamp combination.
You'll still need to level shift the gate drive for Q1 so that the gate is 5V higher than the source terminal when the FET is turned on.
I've used the IRLZ44 singled ended with the 16F684 like this: