App note: Extending the input voltage of op-amps

An app note on extending the  input voltage range of standard op-amps:

Using its own output to bootstrap a low-dropout voltage regulator (MAX6771) with high input-voltage range (up to 76V), this circuit extends the input range of a CMOS op amp (MAX4162) while preserving its high input impedance and very low input bias current (< 1pA).

Thanks rsdio!