A highly detailed, professional electronics schematic diagram for a 3.3V dual-PWM controlled square wave audio generator for headphones. The schematic is drawn in a clean, modern vector engineering style with a white background and sharp black lines. The diagram must clearly show two input pins labeled "PWM_AMP" and "PWM_FREQ", and one output section with a 3.5mm headphone jack. The circuit includes a low-pass RC filter connected to the non-inverting input of a dual Rail-to-Rail operational amplifier IC (labeled options: TS922, TLV2372, or MCP6022) configured as a voltage buffer. The output of the buffer goes through a 1k pull-up resistor to the drain of an N-channel MOSFET transistor (2N7000 or BS170), which is gated by the "PWM_FREQ" pin via a 220-ohm resistor. The audio output features a 100uF DC-blocking coupling capacitor leading to the headphone jack, with the ground of the jack connected to a virtual ground (half-supply 1.65V) created by a 10k/10k resistor voltage divider and the second stage of the op-amp. Every component has clear schematic symbols for resistors, capacitors, transistors, and ICs. Crisp layout, engineering design blueprint, high technical accuracy, no artistic artifacts.