| 摘要 |
A below-ground sensor interface amplifier is powered by no negative supply voltage, but the amplifier nevertheless senses an input voltage signal below ground potential. The amplifier outputs an output voltage signal that varies proportionately to the input voltage. For an input voltage beginning below ground potential and increasing past ground potential, the amplifier outputs an output voltage that remains between ground potential and a supply voltage. The output voltage increases proportionately to the increase of the input voltage. As the input voltage increases, a gate voltage on a first transistor begins to increase starting at the input voltage at which a second transistor is forced to turn on. The amplifier senses input voltages more than one threshold voltage below ground potential without using a below-ground supply voltage. The gain of the amplifier, as well as the lower limit and the size of the amplifier's voltage operating range are programmable.
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