pulse width modulation

[audioguru2]

Kevin,
If the output of your 2-inverter oscillator is bad, then perhaps you are not using a series resistor that has a high enough value (10K minimum).
Also, maybe your output is from the wrong inverter.

 

[Kevin Weddle]

The circuit is correct. The problem is that the classic oscillator has a capacitor charge discharge to it. This makes the square wave not so square.

 

[audioguru2]

The CMOS inverters in a 2-inverter oscillator have a voltage gain of about 100 each. Therefore the charge/discharge of the capacitor is amplified 10,000 times, plus the circuit has positive feedback to speedup the switching even more. The outputs of all the 2-inverter oscillators that I have built and seen are very good and fast square waves.
If the output is taken from the 1st inverter that has the capacitor in series with its input, or if its series resistor or the other resistor is too low in value, then the square wave will have rounded corners.
I agree that adding an inverter to the output of a 2-inverter oscillator makes the square wave even better.