R
raf
- Jan 1, 1970
- 0
Hi,
i am working on an Electronic control unit. I have a current sensing
circuit for motor (high side sensing) in which a differential amplifier
used to sense the current from shunt resistors and to amplify it. In
this ckt two transistors are added to the input terminals of the op amp
(one pnp and anothet npn) whose emitters are connected. I am sure that
these transistors are to maintain the CMRR of the ckt by decreasing the
common mode voltage effect.
Could anyboday have idea how these transistors help to increase the
CMRR of the op amp in case of change in resistor values(tolerances)
Thanks in advance
i am working on an Electronic control unit. I have a current sensing
circuit for motor (high side sensing) in which a differential amplifier
used to sense the current from shunt resistors and to amplify it. In
this ckt two transistors are added to the input terminals of the op amp
(one pnp and anothet npn) whose emitters are connected. I am sure that
these transistors are to maintain the CMRR of the ckt by decreasing the
common mode voltage effect.
Could anyboday have idea how these transistors help to increase the
CMRR of the op amp in case of change in resistor values(tolerances)
Thanks in advance