The circuit I used is an op amp output pin connect to AD7740 input pin.
I need input span -0.15V to +2.5V for AD7740.
But input pin of AD7740 must not be lower than -0.3V.
If the output of op amp series with a resistor than a shottky diode to the GND pin,
it seem can protect AD7740 from input pin to lower than -0.3V.
The shottky diode forward voltage vary with operation temperature.
I cannot keep the input span -0.15V to +2.5V.
Can you suggest how can I do?
OP -------- R -------+----------- AD7740