Re: Duty cycle to voltage...
Hi...
Assuming that the amplitude of input square signal is 12 V, you may get first an inversor. If the output sholud be 0 when input signal is 12 V, 0% duty, this may significates that in this moment, input signal is 12 VDC. This improve allows output DC signal increases when pulse width increases.
After this, you can converts the input-inverted-square signal, in a triangle signal, applying, for example, a Miller integrator. Based in triangle amplitude (that is proportional to pulse width), you may get the DC signal with, for example, simple diode-RC schematic; keeping low output ripple.
Typically, this solution should be non-linear.