DC current regulator insensitive to conducted EMI

摘要

A DC current regulator circuit comprises a first circuit node ( 32 ) which is operable to receive an external input voltage. A transistor (M 1 ) has an input, a first leg and a second leg. The first leg of the transistor is isolated from the first circuit node ( 32 ). An amplifier ( 10 ) has an output connected to the input of the transistor (M 1 ), a first amplifier input for receiving a reference voltage (VREF) and a second amplifier input connected to the first circuit node ( 32 ). A low-pass filter ( 33 ) connects between the output of the amplifier and the first circuit node ( 32 ). A current mirror ( 36 ) connects in series with the second leg of the transistor (M 1 ) and has a first branch ( 38 ) for providing a regulated output current and a second branch ( 37 ) which connects to the first circuit node ( 32 ). The current regulator has reduced sensitivity to conducted EMI received at the first circuit node ( 32 ).