3.3V Digital to 5V Analog Output
You could replace the MOSFET with a single CMOS logic converter - this will drive the filtering circuit and be somewhat more accurate because it has a push pull output and can work up to much higher frequencies than an open-drain MOSFET and 1 kohm resistor. Use a single-element logic device to keep board usage small. I'm sure TI have a device that fits the bill - look for TTL to CMOS inverter or buffer.