Patent ID: 8143881
Filing Date: 2012-03-27
Classification: G01R

Abstract:
1. A current measuring apparatus comprising: a shunt resistor to receive current to be measured; an operational amplifier comprising a non-inverting terminal, an inverting terminal, and an output terminal, wherein a first terminal of the shunt resistor is grounded via a first resistor and a second resistor in series, a node between the first and second resistors is connected to the non-inverter terminal of the operational amplifier, a second terminal of the shunt resistor is connected to the inverting terminal of the operational amplifier via a third resistor, the inverting terminal of the operational amplifier is connected to the output terminal of the operational amplifier via a fourth resistor; and an amplifier comprising a non-inverting terminal, an inverting terminal, and an output terminal to output a voltage to be measured, wherein the output terminal of the operational amplifier is also connected to the non-inverting terminal of the amplifier, the inverting terminal of the amplifier is connected to the output terminal of the amplifier via a fifth resistor, the inverting terminal of the amplifier is also grounded via a sixth resistor, the measured voltage is directly proportional with the measured current.