Current sense amplifier circuit and trimming method of offset referred to input voltage

A current sensing amplifier circuit, which is configured to operably sense a to-be-sensed current flowing through a sensing resistor, wherein the sensing resistor has two ends correspondingly coupled to a first input end and a second input end of the current sensing amplifier circuit;

• the current sensing amplifier circuit comprising:
• an amplifier, which is configured to operably generate an output voltage correlated with the to-be-sensed current according to a first input voltage at the first input end and a second input voltage at the second input end in a normal operation mode;
• a first resistor coupled between a reference voltage and a non-inverting input end of the amplifier, wherein a resistance of the first resistor is a sum of a first resistance plus a first error resistance;
• a second resistor coupled between the output voltage and an inverting input end of the amplifier, wherein a resistance of the second resistor is a difference of the first resistance minus the first error resistance;
• a third resistor coupled between the first input end and the non-inverting input end of the amplifier, wherein a resistance of the third resistor is a difference of a second resistance minus a second error resistance;
• a fourth resistor coupled between the second input end and the inverting input end of the amplifier, wherein a resistance of the fourth resistor is a sum of the second resistance plus the second error resistance;
• and
• a current source circuit, which is configured to operably generate a trimming current in a trimming mode according to the first input voltage and the reference voltage, according to the second input voltage and the reference voltage, or according to an input common mode voltage and the reference voltage, and the current source circuit is configured to operably provide the trimming current to trim an offset referred to input (RTI) voltage generated due to the first error resistance and the second error resistance in the normal operation mode;
• wherein the current source circuit is coupled to:
• a first node between the first resistor and the non-inverting input end, a second node between the second resistor and the output voltage, a third node between the third resistor and the non-inverting input end, or a fourth node between the fourth resistor and the inverting input end;
• wherein in the trimming mode, the first input end is electrically connected to the second input end, so that the first input voltage has a same voltage level as the second input voltage.